Grits and Greens Soufflé

Name: Grits and Greens Soufflé
Ingredients: 2 Tbsp. (30 ml) olive oil; 4 oz (112 g) collard greens, fresh or frozen, cleaned and chopped; Pinch of sugar (optional); Salt and crushed red pepper flakes, to taste; 1 Tbsp. (15 ml) white wine vinegar or other vinegar; ¾ cup (180 ml) water; ⅓ cup (95 g) stone-ground grits; 2 Tbsp. (28 g) butter; 2 Tbsp. (16 g) flour; 1 cup (235 ml) milk; ⅓ cup (40 g) shredded cheddar cheese (optional); 4 eggs, at room temperature, separated; ¼ tsp. cream of tartar