Preheat the oven to 450°. Toss **potatoes** with oil, salt, and pepper, and roast for 22 minutes (until browned and tender).
Add oil to a large pan. When hot, add the **brussels sprouts**, **chili paste**, salt, and pepper. Saute, stirring occasionally, until browned and tender, about 5 minutes. Transfer to bowl.
Add more oil to pan, then add **scallion whites** and **brown sugar**, and season. Cook 30s-1min, until lightly browned and softened. Add the **beans** and 1/8 cup water. Cook 3-4min, stirring occasionally and mashing the beans as they soften until the mixture is thickened. Taste and season if needed.
Combine the **sour cream** and **vinegar**, seasoning to taste.
Warm the **tortillas**, fill with beans and brussels sprouts, and top with seasoned sour cream and scallion greens. Serve with potatoes on the side.