Heat the oil in a 23cm or 25cm non-stick frying pan over a medium heat. Add the sliced onions and courgettes and sauté for 2 to 3 minutes, until coloured.
Dry the sliced potatoes with a clean kitchen towel and add them to the pan, tossing to combine. Season generously with salt and pepper. Reduce the heat to low and cover the pan with a lid or plate. Cook gently for 10 to 15 minutes, until the potatoes are cooked through and lightly golden. Turn them over once or twice and shake the pan occasionally to ensure they cook evenly.
Break the eggs into a large bowl.Add a good pinch of salt and pepper, then whisk lightly with a fork.
When the potato mixture is cooked, quickly stir in the beaten eggs, pressing them down gently. Add the goat’s cheese to the potatoes along with half of the herbs. Cook on a low heat for about 5 minutes, until there is virtually no raw egg mixture left on top of the frittata, pushing down the sides with a spatula for a curved edge. Carefully invert the frittata onto a flat plate and slide it
back into the pan. Cook for another 5 minutes, until just cooked through but still moist in the centre.
Turn the frittata out onto a chopping board and cut into
wedges. Sprinkle with the remaining herbs. Serve warm or cold with the salad leaves.