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close up shot of mashed potatoes with caramelized onions and fresh thyme

Vegan Caramelized Onion Mashed Potatoes

A recipe for Vegan Mashed Potatoes made with delicious caramelized onions mixed in. Your new favorite Vegan Thanskgiving side!
4.82 from 16 votes
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Course: Vegetarian Sides
Cuisine: American
Prep Time: 15 minutes
Cook Time: 40 minutes
Total Time: 55 minutes
Servings: 8 servings


Mashed Potatoes

  • 6-7 medium peeled potatoes a mix of 75% russet and 25% yukon potatoes works best
  • 6-8 Tablespoons vegan butter make sure the butter is room temperature
  • 2 Tablespoons full-fat coconut milk can be replaced with additional 2 Tbsp of vegan butter
  • 1 teaspoon garlic powder
  • salt & pepper to taste
  • fresh thyme optional

Caramelized Onions

  • 1 large thinly sliced yellow onion
  • 2 Tablespoons vegan butter or oil
  • salt & pepper to taste


  • Before starting, peel your potatoes and cut into large but equal sized pieces. Slice your onions into thin long slices and set aside.
  • Add the peeled potatoes to a strainer and rinse to remove some of the starch. Then, add the potatoes to a large pot and fill the pot with cold water until the potatoes are just covered by about ½" of water. Add a generous amount of salt to the water until the water tastes salty.
  • Bring the pot of potatoes to a boil and cook for 15-20 minutes until you can pierce the potatoes with a fork/knife and they are the same consistency all the way through. You don't want to overcook your potatoes or the mashed potatoes will be too watery, so I recommend checking at the 12 minute mark to be safe.
  • While the potatoes are cooking, caramelize the onions. Add 2 Tbsp of vegan butter/oil to a frying pan and turn on the burner. Once the butter is bubbling and melted, add in the onion slices. Pan fry at low heat until onions are browned; around 20-40 minutes depending on preference. Stir frequently so that the onions do not burn. Once the onions are done, season with salt and pepper to your liking and set aside.
  • As soon as the potatoes are cooked, strain and add back to the pot. Use a potato masher to roughly mash the potatoes while still hot.
  • Once the potatoes are somewhat mashed, add in 6-8 Tbsp of room temperature/melted butter to the pot and continue mashing until the potatoes are mostly smooth with some chunks. How large your potatoes are and how buttery you like your mashed potatoes will determine how much butter you use, so feel free to add in more or less to your liking! For creamier mashed potatoes, add in the 2 Tbsp of coconut milk at this time as well. Season with the garlic powder, fresh thyme, and additional salt & pepper until your desired flavor is reached. As a final step, gently fold in the caramelized onions.
  • Top with additional fresh thyme or a homemade gravy and serve warm. Enjoy!


  • I use about 75% Russet potatoes and about 25% Yukon potatoes for my perfect mix of Mashed Potatoes.
  • Make sure to boil your potatoes in large chunks so they don't absorb too much water.
  • I like to use room temperature for mashed potatoes so that the potatoes can fully absorb all the butter. Also, make sure to mash the butter and potatoes together while the potatoes are still hot for the best results!
  • Using a Potato Masher is the best way to enjoy potatoes that are not over-mashed.
  • Mashed potatoes are best enjoyed on the day the potatoes are cooked. If you are making an hour or two ahead of eating make sure to keep warm and covered so the potatoes do not dry out.
  • Leftovers can be stored in a closed container in the fridge for 3-4 days. 


Calories: 221kcal | Carbohydrates: 30g | Protein: 4g | Fat: 10g | Saturated Fat: 3g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 4g | Trans Fat: 1g | Sodium: 101mg | Potassium: 717mg | Fiber: 4g | Sugar: 2g | Vitamin A: 538IU | Vitamin C: 33mg | Calcium: 24mg | Iron: 1mg
Tried this recipe?Mention @shortgirltallorder or tag #sgtoeats!