Make curry: Heat a large pot or dutch oven of medium-high heat and add the remaining vegetable oil. Add the bell pepper, onion, broccoli, and potato to the bowl and cook until the bell peppers and onion begin to brown, about 5 minutes. Then add the yellow curry paste and mix well to coat the vegetables, cooking another 2-3 minutes until the paste releases its flavors. Then pour in the coconut milk and season with brown sugar, salt, and red chili pepper flakes (or full chilis, if using). Bring to a boil, then cover and cook about 20 minutes, or until the potatoes are soft and cooked through. Then add tofu, cilantro, and lime juice and cook 5 minutes more. Taste to ensure desired seasonings, then remove from heat.
1 tablespoon peanut oil, 1 large bell pepper, 1 small yellow onion, 1 large russet potato, 2 cups broccoli florets, ½ cup yellow curry paste, 2 13.5-ounce cans full fat coconut milk, 1 teaspoon salt, ½ teaspoon red chili pepper flakes, 1 tablespoon brown sugar, ½ cup fresh cilantro, 3 tablespoons lime juice