Step 1

Heat oven to 220C/200C fan/gas 7 with a muffin tin inside. Heat the oil in a frying pan and fry the leek for about 4 mins, stirring regularly, over a medium-high heat to soften it. Stir in the spinach and cook for 1 min until wilted down, then set aside to cool slightly.

Step 2

Beat the eggs, dill, yogurt and feta together in a jug with black pepper and the garlic. Add the leeks and spinach, and stir well. Take the muffin tin out of the oven and drop in four muffin cases, add the egg mixture and bake for 15-18 mins until set and golden.

Step 3

Meanwhile, mix the balsamic vinegar with the tahini and 1-2 tbsp water in a bowl to make a dressing, then toss with the vegetables and olives. Pile onto plates, carefully remove the paper cases from the frittatas and serve.