Vegan Caramelized Onion Mashed Potatoes – Creamy Best Side

I used to think mashed potatoes without butter and cream were basically a sad pile of beige. Then one Thanksgiving I ran out of dairy halfway through cooking and had to improvise with olive oil and oat milk, and honestly? Nobody at the table noticed. My uncle Gary asked for seconds twice, and he is a man who puts butter on his butter.

The real magic here is the onions. You take a big pile of sliced onions, give them 35 unhurried minutes in a hot pan, and they collapse into jammy, sweet, deeply golden strands that taste almost like caramel. Fold those into fluffy Yukon Gold potatoes with garlic, olive oil, and a splash of warm oat milk, and you get a side dish that steals the show from the main event.

It is also forgiving. If your onions are a little darker than mine, great. If your potatoes are lumpy because you got distracted by your phone, also fine. This is comfort food, not a baking exam. You're doing better than you think.

About the Ingredients

3 lb (1.36 kg) Yukon Gold potatoes, peeled and cut into 2-inch chunks

Yukon Golds are the gold standard for mashing because their medium starch turns creamy instead of gluey. If you can only find russets, use them but add 2 extra tablespoons of olive oil since russets are drier.

3 large yellow onions (about 2 lb / 900 g), thinly sliced

Yellow onions have the right sugar balance to caramelize without turning bitter. Sweet Vidalia onions work too and brown faster, so shave 5 minutes off the cook time.

1/3 cup (80 ml) extra-virgin olive oil, divided

Use a fruity, everyday olive oil, not your fancy finishing bottle, since heat mutes delicate notes. Cold-pressed avocado oil is a neutral-flavored swap if you dislike olive oil's bite.

1 cup (240 ml) unsweetened oat milk, warmed

Oat milk is the creamiest plant milk for mashing and won't separate. Unsweetened soy milk is the closest substitute; avoid almond milk, which stays thin and watery.

4 garlic cloves, minced

Fresh garlic gives a sharper, sweeter bite than jarred. If you only have garlic powder, use 1 teaspoon stirred in with the oat milk instead.

1 1/2 tsp fine sea salt, plus more for the potato water

Fine sea salt dissolves evenly into the mash. Kosher salt works but use 2 teaspoons since the flakes are larger and less dense.

1/2 tsp freshly ground black pepper

Fresh-cracked pepper tastes brighter than pre-ground. White pepper is a good swap if you want the mash to stay perfectly snow-white.

2 tbsp (28 g) vegan butter, optional but lovely

A cultured vegan butter like Miyoko's adds a tangy, buttery finish. Skip it entirely and add one more tablespoon of olive oil if you don't keep it on hand.

2 tbsp fresh chives, finely chopped, for garnish

Chives add a fresh oniony pop and a hit of green. Thinly sliced scallion greens or a pinch of fresh thyme leaves both work beautifully.

Tips & Tricks

Don't rush the onions

Real caramelization takes 30 to 35 minutes over medium-low heat. Cranking the burner gives you burnt edges with raw centers, which is the number one mistake with this dish.

Warm your oat milk before adding it

Cold liquid shocks the potatoes and makes them seize up and turn gummy. Microwave it for 45 seconds until it's warm to the touch.

Salt the boiling water like the sea

Potatoes absorb salt only while they boil, so season the water generously. You cannot fully fix bland potatoes after they're mashed.

Mash while hot, then rest

Potatoes turn gluey when they cool and get overworked. Mash immediately after draining, fold in the onions last, and serve within 20 minutes for the fluffiest texture.

Step-by-Step Instructions

1. Boil the potatoes

Place the potato chunks in a large pot and cover with cold water by 2 inches. Add 2 tablespoons of salt, bring to a boil over high heat, then reduce to a gentle simmer at 200 F (93 C) and cook for 18 to 20 minutes, until a knife slides in with no resistance and the potato falls off easily.

2. Caramelize the onions

While the potatoes cook, heat 3 tablespoons of olive oil in a wide skillet over medium-low heat at 325 F (163 C). Add the sliced onions and 1/2 teaspoon salt, stir to coat, and cook for 30 to 35 minutes, stirring every few minutes, until they are deep golden brown, jammy, and reduced to about a quarter of their original volume.

3. Bloom the garlic

Push the onions to one side of the skillet, add the remaining olive oil and the minced garlic to the empty spot, and cook for 45 to 60 seconds at 300 F (149 C) until fragrant but not browned. Stir the garlic through the onions and kill the heat.

4. Warm the oat milk

Microwave the oat milk in a heatproof cup for 45 seconds, or warm it in a small saucepan over low heat at 150 F (66 C) until steamy but not simmering. Warm liquid is the secret to lump-free, creamy mash.

5. Drain and mash

Drain the potatoes well and return them to the hot pot for 1 minute to steam off excess moisture. Mash with a ricer or potato masher until smooth, then stir in the vegan butter, warm oat milk, remaining salt, and black pepper until glossy and cohesive.

6. Fold in the onions

Gently fold three-quarters of the caramelized onions into the potatoes with a spatula, keeping some texture rather than whipping them in. Taste and adjust salt, keeping in mind the onions carry a lot of sweetness.

7. Garnish and serve

Spoon the mash into a warm serving bowl, swirl the top with the back of a spoon, and crown it with the reserved onions and fresh chives. Serve immediately at 140 F (60 C) or hotter for the best texture.

Delicious Variations

Roasted Garlic Version

Roast a whole head of garlic at 400 F (204 C) for 40 minutes, then squeeze the soft cloves into the potatoes for a mellow, nutty twist.

Herb-Forward Version

Stir in 1 tablespoon of chopped fresh rosemary and 1 tablespoon of thyme with the onions for a woodsy, holiday-ready flavor.

Spicy Skillet Version

Add 1/2 teaspoon of smoked paprika and a pinch of cayenne to the onions in the last 2 minutes for a smoky, gently spicy mash.

How to Store Vegan Caramelized Onion Mashed Potatoes

Frequently Asked Questions

If you make these vegan caramelized onion mashed potatoes, I would love to hear how they turned out. Drop a comment below, tell me what you served them with, and snap a photo for Instagram so I can cheer you on. You're doing better than you think.

Vegan Caramelized Onion Mashed Potatoes

Vegan caramelized onion mashed potatoes are silky, buttery, and dairy-free, with sweet golden onions folded in for a side dish everyone devours.

★★★★½ 4.8 (214 ratings)

15 minPrep time35 minCook time6Servings285 kcalCalories

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🧂 Ingredients

• 3 lb (1.36 kg) Yukon Gold potatoes, peeled and cut into 2-inch chunks
• 3 large yellow onions (about 2 lb / 900 g), thinly sliced
• 1/3 cup (80 ml) extra-virgin olive oil, divided
• 1 cup (240 ml) unsweetened oat milk, warmed
• 4 garlic cloves, minced
• 1 1/2 tsp fine sea salt, plus more for the potato water
• 1/2 tsp freshly ground black pepper
• 2 tbsp (28 g) vegan butter, optional but lovely
• 2 tbsp fresh chives, finely chopped, for garnish

📋 Instructions

1. 1Boil the potatoes — Place the potato chunks in a large pot and cover with cold water by 2 inches. Add 2 tablespoons of salt, bring to a boil over high heat, then reduce to a gentle simmer at 200 F (93 C) and cook for 18 to 20 minutes, until a knife slides in with no resistance and the potato falls off easily.
2. 2Caramelize the onions — While the potatoes cook, heat 3 tablespoons of olive oil in a wide skillet over medium-low heat at 325 F (163 C). Add the sliced onions and 1/2 teaspoon salt, stir to coat, and cook for 30 to 35 minutes, stirring every few minutes, until they are deep golden brown, jammy, and reduced to about a quarter of their original volume.
3. 3Bloom the garlic — Push the onions to one side of the skillet, add the remaining olive oil and the minced garlic to the empty spot, and cook for 45 to 60 seconds at 300 F (149 C) until fragrant but not browned. Stir the garlic through the onions and kill the heat.
4. 4Warm the oat milk — Microwave the oat milk in a heatproof cup for 45 seconds, or warm it in a small saucepan over low heat at 150 F (66 C) until steamy but not simmering. Warm liquid is the secret to lump-free, creamy mash.
5. 5Drain and mash — Drain the potatoes well and return them to the hot pot for 1 minute to steam off excess moisture. Mash with a ricer or potato masher until smooth, then stir in the vegan butter, warm oat milk, remaining salt, and black pepper until glossy and cohesive.
6. 6Fold in the onions — Gently fold three-quarters of the caramelized onions into the potatoes with a spatula, keeping some texture rather than whipping them in. Taste and adjust salt, keeping in mind the onions carry a lot of sweetness.
7. 7Garnish and serve — Spoon the mash into a warm serving bowl, swirl the top with the back of a spoon, and crown it with the reserved onions and fresh chives. Serve immediately at 140 F (60 C) or hotter for the best texture.

👨‍🍳 Chef's Note: The onions are the star here, so taste them before folding them in. If they taste flat, add a pinch of salt and a tiny splash of balsamic vinegar to wake them up.

Servings: 6

Cuisine: American

Course: Side Dish

Nutrition (per serving): 285 kcal · 5g protein · 42g carbs · 11g fat

Written by Sofia Ramirez

Sofia writes about parenting and family wellness, exploring the messy, joyful reality of raising kids. She offers relatable stories and practical advice on everything from sleep training to managing screen time, always with a dose of humor.