1 cup Puy (French) lentils
2 bay leaves
2 teaspoons cumin seeds
2 teaspoons coriander seeds
5 tablespoons olive oil, plus extra to finish
1 medium onion, roughly chopped
2 garlic cloves, crushed
1 1/4 cups Greek yogurt
2 cups baby spinach leaves
3 tablespoons chopped cilantro
3 tablespoons chopped mint
Juice of 1 lemon
Salt and black pepper
14 ounces best-quality puff pastry
1 egg, beaten