Heat 2 tablespoons of the butter in a stove top pressure cooker. Add onion, ginger, garlic, bell peppers and saut until the onion turns translucent, about 5 minutes. Add the cauliflower, potatoes, tomatoes, peas, and 2 teaspoons salt; pour in the water; and stir well. Secure the lid and pressure cook 2 to 3 whistles or about 15 minutes on medium heat.