Peel and chop potatoes. Place in a pot, cover with cold water and bring to boil over medium heat. Cook until soft. Drain well, add butter and sour cream (or half and half) and mash. Season with salt and pepper to taste.
In a large skillet, heat up olive oil. Add one tablespoon of butter and let melt. Add minced garlic and chopped onions. Saute, stirring often until fragrant, translucent and some pieces are golden.
Add second tablespoon of butter. Stir in, melting, and cook onions until golden brown and caramelized. Add brown sugar and soy sauce. Stir in. Remove from heat.
Stir in caramelized onions with mashed potatoes. Serve right away or cool completely, cover with saran wrap and store in the fridge for the next day.
Notes
One cup equals one serving. The nutritional value is for mashed potatoes with sour cream. To make ahead: cool completely, cover with saran wrap and store in the fridge for the next day. You can reheat this dish in a skillet on the stove or place them in a casserole dish and reheat in the oven. Add milk or sour cream and butter as needed.