1. Start by trimming some but not all the fat from the lamb. It's essential to leave some fat for flavor and moisture. Cut the lamb into cubes about 1 1/2 inches square.
2. In a bowl, whisk together onion powder, garlic powder, oregano, ground rosemary, ground cumin, paprika, black pepper, lemon juice, and olive oil to create a flavorful marinade. This mixture will enhance the taste of your lamb significantly.
3. Place the lamb cubes into a Ziploc bag, pour the marinade over them, and seal the bag. Massage the marinade into the lamb and let it marinate in the fridge for several hours or overnight. This step is crucial for maximum flavor.
4. When you’re ready to cook, drain the marinated lamb cubes in a colander and let them come to room temperature. This ensures even cooking on the grill.
5. In the meantime, preheat your grill to high heat. If you’d like, you can spray it with non-stick grill spray to prevent sticking.
6. Prepare your veggies by cutting the ends off the zucchini and peeling the red onions. Cut both into pieces about 1 1/2 inches wide, similar in size to the lamb cubes.
7. Now it’s time to thread the skewers! Begin by placing a piece of lamb onto the skewer, followed by a piece of zucchini and a piece of red onion. Repeat until the skewer is filled, leaving some space between each piece to allow for even cooking.
8. Brush the assembled kabobs on all sides with olive oil. This will help them achieve a nice grill mark and prevent sticking.
9. Place the skewers on the grill. Immediately lower the temperature to medium-high. Grill the kabobs for about 8 to 12 minutes, turning them every 3 minutes. Look for nice grill marks, which indicate they are cooking well.
10. Using an instant-read meat thermometer, check the internal temperature of the lamb. For medium rare, aim for 145F/65C; for medium, it should be 160F/70C; and for well-done, it should reach 170F/75C.
11. When done, remove the kabobs from the grill and let them rest for a few minutes. Serve hot, and consider pairing them with low-carb pita bread and Tzatziki sauce if desired.
