Preheat the oven to 350 degrees. Line a baking sheet with foil and drizzle with the olive oil. Add the cherry tomatoes and garlic and toss with your fingers until well-covered with oil. Add a little salt and pepper. Place tray in the oven on the middle shelf.
Roast until blistered, about 30-45 minutes. Start checking them at 25 minutes so they don’t burn. When nicely blistered, place the tomatoes in a bowl and set aside as a topper for the omelette.
Make the avocado with fresh lemon topping
Rinse each whole avocado. Cube them and set aside in a bowl to use as an omelette topper. (If doing this in advance, place the avocado pits in the bowl with the cubes to keep them from turning brown.) Squeeze a little lemon juice on the cubed avocado and lightly sprinkle with salt. Set aside as a garnish for the omelette.
Make the omelette
Heat olive oil on medium and sautée lettuce until wilted and a little browned. When done, reduce heat to medium-low and add beaten eggs, scallions, feta, and olives. Cover pan with a lid.
Allow eggs to cook slowly and set, about 5 minutes. When the first side is lightly browned, flip it to the second side. Cook without the lid until done. If it’s easier to scramble the eggs, stirring as they cook, this is perfectly fine.
Divide the eggs on the plates and top each serving with blistered tomatoes and avocado. Add salt and freshly ground pepper to the assembled dish to taste. Serve with your choice of toasted bread. (A Greek restaurant would serve warmed pita brushed with olive oil.)