Preheat the oven
The first step towards making a simple frittata is to preheat your oven to 350 degrees F before you put 2 or 3 tablespoons of olive oil in a frying pan and heat it. You are now required to sauté the onion until it becomes translucent. Add any other vegetable if you want to at this stage and cook it until it gets soft. You can drain the vegetables if they release a lot of water.
Beat the eggs
You may beat the eggs while the vegetables are being cooked. The other option is to put them in a blender before you pour them over the vegetables.
Move the mixture with a spatula
Using a spatula, you should move eggs and vegetables around just like you do while scrambling eggs. At this stage, you may add the required quantity of salt and pepper. It is highly recommended that you do not add salt before this stage because salt brings out water in the vegetables and you would surely not want that. Until some minor solidification occurs, you need to continue to move the mixture with a spatula.
Place the frittata in the oven
Put the frittata in the oven for about 30 minutes. Once it gets firm, you should sprinkle some feta over it and place it in the oven again until it is brown. When it is done, you may garnish it with shredded fresh basil.