1. In a bowl, combine garlic, lemon juice, olive oil, cardamom, cloves, and, if desired, 1/2 teaspoon salt.
2. On a plate, mix sesame seed and dill.
3. Rinse salmon steaks, drain, add to oil mixture, and turn to coat. Lift out steaks, 1 at a time, and lay each cut side in seed mixture to coat. Place in a single layer on a plate.
4. Lightly oil a barbecue grill over a solid bed of medium coals or a gas grill on medium heat (you can hold your hand at grill level only 5 to 6 seconds). Lay fish on grill. Close lid on gas grill.
5. Cook fish until browned on bottom, 3 to 4 minutes. Turn with a wide spatula and continue to cook until fish is opaque but still moist-looking in center of thickest part (cut to test), 4 to 6 minutes more.
6. With spatula, transfer fish to plates. Season to taste with salt and juice from lemon wedges.
Garnish with dill springs, if desired.