Wash the mint, shake dry and finely chop the leaves of 3 stems. Peel onion and cut into fine cubes. Knead minced onion, chopped mint, mustard, egg, milk and breadcrumbs, season with salt, pepper, cumin and curry.
Form approx. 20 balls from the chopped mass. Heat the oil in a large pan. Fry the balls for about 10 minutes, turning them over. Wash the cucumber, grate it and squeeze it lightly. Peel garlic and chop finely.
Mix yoghurt, grated cucumber and garlic and season with salt and pepper. Serve meatballs with yoghurt dip and garnish with mint.