Add the oil to the pan and cook the leek, bacon and garlic for 5 minutes or until leek is softened.
Meanwhile, whisk the eggs and the sour cream in a large jug.
Add the grated cheese to the eggs and season with salt & pepper.
Reduce the heat to medium-low and pour the egg mixture into the pan and cook for about 8 minutes, until the edges are set.
Break up the feta and scatter evenly around the frittata.
Place fry-pan (oven-proof) in the broiler or grill and cook for 3-5 minutes or until set.
Slice and serve with a Parmesan & arugula (rocket) salad.
This recipe is great reheated for lunch the next day. The frittata can also be cooked in the oven at 375°F (180°c) for 15 minutes. If you don't have an oven-proof fry-pan, cook the leek, bacon and garlic in a fry-pan, then place it in a baking dish and pour the eggs over the top. Bake in the oven for 30 minutes at 375°F (180°c).