Heat the oil in a non-stick pan over medium heat. Add the chicken sausage, onions, and peppers. Sauté for about 4 to 5 minutes.
Add the eggs and tomato to the pan. Cook for approximately 1 minute without stirring, until egg mixture begins to set.
Using a heat-safe spatula, gently lift the side of egg and tilt the pan to allow uncooked egg to flow underneath. Cook until set. Repeat procedure until egg is no longer runny.
Toast the bread.
Add the cheese and fold the omelet in half to melt.