Heat a 10” skillet over medium-high heat and add the olive oil. Once oil is shimmering, add the bell peppers and onions and season with thyme, salt and pepper. Cook until wilted, about 5-7 minutes. Pour over the eggs and tilt the pan to let the egg fill the bottom of the pan. Sprinkle with the tomatoes and cook for 2 minutes until eggs set on the bottom, then run a spatula around the edges and under the omelet to loosen it from the pan and flip it over. Let cook for 2 more minutes and then fold in half. Press down with the spatula to tighten the omelet.

Transfer the finished omelet to a plate and top with avocado. Serve with greens, if preferred.