For the tandoori sauce, peel garlic, chop finely and mix with yoghurt, mustard and honey. Season with salt, pepper and 1 teaspoon cumin.
Oil the skewers. Clean, wash and cut the peppers, zucchini and fennel into large pieces. Clean, wash and halve or quarter radishes. Peel and quarter onions. Put the vegetables alternately on the skewers.
Spread with approx. 1⁄4 Tandoori sauce. Marinate for about 1 hour.
Drain the skewers and place them in the grill trays. Put them on the hot grill. Grill the skewers for 10-15 minutes while turning. Add the rest of the tandoori sauce.