Presoak some 15 cm (6 inch) wooden skewers in warm water. Combine the lentils with the stock, bay leaf, cinnamon stick and cardamom pods in a pan, season with salt and simmer for 10 minutes or until the lentils are soft.
Meanwhile, to make the yogurt relish, mix together the coriander, mint, onion and yogurt and add salt and pepper to taste.
Cook the peas in boiling water. Drain the lentils and remove the bay leaf, cinnamon stick and cardamom pods. Transfer the peas and lentils to a food processor or blender and process briefly. Stir the pea mixture into the curry paste and use 2 teaspoons to shape the mixture into small balls. Refrigerate until ready to cook.
Put 3—4 balls on each skewer. Heat a frying pan and spray it with oil. Fry the skewers (in batches if necessary) over medium heat for 2 minutes undisturbed, then turn and cook the other side. Serve hot with the yogurt relish.