Heat the oil in a wok or large non-stick skillet on medium to medium-high. Add the cauliflower and garlic; stir-fry until the cauliflower is nearly tender, but not mushy. Stir in the soy sauce and sesame oil. Push the cauliflower to one side of the pan; pour in the beaten egg. Lightly scramble the egg briefly then mix into the cauliflower. Add the green onion and pepper, if using, and toss.