Heat omelette pan or small skillet sprayed with cooking spray on medium-high heat. Add onions, chilies, coriander and cumin seed; cook and stir 2 min. or until onions are crisp-tender. Add egg mixture; cook 3 to 4 min. or until set, lifting edge with spatula and tilting pan to allow uncooked portion to flow underneath to cook. When egg mixture is set but top is still slightly moist, slip spatula underneath omelette, tip skillet to loosen and gently fold omelette in half.