Start by making the dill yoghurt. Pick and finely chop the dill and place half of it in a bowl with the yoghurt. Peel and finely grate in the garlic, squeeze in the lemon juice and season to perfection. Add 1 tablespoon of oil, mix well, and leave to one side.
Place the spinach in a saucepan over a low-medium heat with 1 teaspoon of oil and cover with a lid. Reduce the heat to low and cook until the spinach is wilted. Tip into a sieve and leave to drain.
Drain the lentils and tip into a food processor. Blitz until creamy, then add one of the eggs and blitz again. Spoon into a bowl and add the remaining dill and egg, and a pinch of salt and pepper.
Pick and finely chop the parsley leaves. Place in a bowl with the breadcrumbs, and crumble in the feta. Squeeze out the excess liquid from the spinach and chop it up. Add to the bowl and mix everything together well.
Place a large non-stick frying pan over a medium heat and add enough olive oil to cover the base. Using a dessertspoon, scoop out servings of the keftedes mixture and ladle them into the hot oil, flattening them slightly.
Fry for 4 minutes on each side, until golden and cooked through. Serve the keftedes hot, with dill yoghurt for dipping and a green salad.