Heat the vegetable oil on a low heat in a large 28cm wide frying pan or cast iron skillet. Pre-heat your grill/broiler to a medium/high heat
Add the spring onion and garlic to the pan and cook for 5 minutes, or until softened
Add the potatoes and cook for another 5 minutes
In a mixing bowl, whisk together the eggs, egg whites, salt and thyme
Pour the egg mixture into the pan, then add the feta all over. Keep it on the hob for 5 minutes to cook the bottom
Put the frittata under the grill for 15 minutes, keep an eye on it regularly as grills can vary in heat so much
If it needs cooking more on the bottom at all, you can pop it back on the hob for 5 minutes
Remove the frittata from the pan and slice up. Serve immediately, or allow to cool and store in the fridge for up to 3 days. You can also freeze frittata, wrap it well and freeze for up to 3 months
Notes
I use a carton of egg whites, plus a couple of eggs for this recipe. This keeps the calorie and fat content down (as egg yolks are high in calories and saturated fat) and it also saves time cracking loads of eggs! Cartons of egg whites are so handy and they are quite readily available now. The brands I know of are Two Chicks and Happy Eggs. I do add a couple of eggs in the mix too, as it lifts the texture and adds a touch of richness.
If you would like to use all whole eggs instead, replace the egg whites with 8 whole large eggs.
I do advise using salt in this recipe, as eggs and potatoes alone can be quite bland and adding salt really lifts the flavour of this dish.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50).
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.