Sage and red onion frittata (sage & Onion Omelet)

Skin and slice the onions. Wash and dry the sage leaves. Heat a little olive oil in a skillet and sauté the onions and the sage over medium heat for 5 minutes.
Beat the eggs in a bowl and add the browned onions and sage. Stir and season with salt and pepper.
Heat 3 tablespoons olive oil in a nonstick skillet. Pour the mixture and let it curdle and brown on both sides. When finished, slide the omelet onto the plate and serve cut into thick slices.