Step 1: Cut the chicken into 1/2-inch cubes. Cut the onion in half widthwise. Cut each half in quarters and break each quarter into individual segments. Thread the chicken cubes onto bamboo skewers alternating with pieces of onion. Arrange the kebabs in a baking dish or foil pan just large enough to hold them. Season on all sides with salt and pepper.

Step 2: Make the Charmoula and spoon half of it over the chicken kebabs, turning the kebabs so they marinate evenly. Cover and let marinate in the refrigerator while you make the sauce and light the grill.

Step 3: Make the sauce: Cut the tomatoes in half widthwise and wring out the seeds. Grate each tomato on the coarse side of a box grater into a mixing bowl. The idea is to grate the tomato flesh. Discard the skin. Stir the remaining Charmoula into the grated tomatoes. Taste for seasoning, adding salt or lemon juice to taste.

Step 4: Set up your grill for direct grilling and preheat to high. Brush and oil the grill grate.

Step 5: Drain the chicken kebabs and arrange on the grate. (Discard the marinade.) Grill until browned on the outside and cooked through, about 3 minutes per side. Serve the chicken kebabs with the Charmoula-tomato sauce for spooning over them, and Moroccan bread or pita on the side.