In a 10-inch ovenproof skillet, heat oil over medium-high. Add scallions and tomatoes, and cook for about 5 minutes. Add the zucchini, season with a little salt and pepper, and cook for about 2 minute more.
Add the eggs, cheese, dill, salt and pepper to the skillet and stir to combine. Use a spoon to help you distribute the tomatoes evenly. Allow to cook, undisturbed, until edges are set, about 2 minutes. Place the skillet into your preheated oven and bake until the top of the frittata is set, about 10-13 minutes.
Allow to cool for a few minutes before slicing. May be served warm or at room temperature.