Soften the onion in a frying pan with some olive oil on a low heat
Beat the eggs in a separate bowl
Add the potatoes, onions and ham with the parsley and plenty of salt and pepper into the egg and mix
Heat a little olive oil in a frying pan. Tip everything into the pan and cook on a moderate heat, using a spatula to shape the frittata
Sprinkle grated cheese on top and place under the grill to golden
Heat a pan with a drizzle of olive oil and add the sliced the halloumi to brown slightly. Turn the halloumi to cook on both sides
Serve a slice of frittata warm with slices of halloumi and a mixed green and avocado salad dressed in lemon juice
Leftover frittata can be eaten cold the following day and makes a great GD friendly snack. The ingredients can be changed to whatever you fancy and it's a great way of using up leftover meat and vegetables.