If using wooden skewers, soak them in water for at least 30 minutes to prevent burning. Metal skewers don’t need soaking and are reusable.
Grill the Kebabs:
Thread the chicken onto the skewers, leaving a little space at the tip and at the bottom to make it easy to work with. Separately, on a small plate, drizzle the Roma tomatoes, quartered red onion, and serrano peppers with a touch of oil for grilling.
Heat the grill over medium-high heat (350℉ to 400℉) and oil the grill grates. To do this, dip a wadded paper towel in a little oil and, using tongs, wipe the oil evenly over the grate. Be careful not to use too much oil, because that’s a surefire way to start a good flare-up—a little goes a long way here.
Place the skewers directly over the heat. Add the tomatoes, onion, and serranos on the exterior of the grill. Cook the veggies just until they are tender and have a nice char, 3 to 4 minutes per side. Grill the chicken for 10 to 15 minutes, turning every 3 to 4 minutes, until the meat is golden brown and cooked through. You’ll want a nice char around the edges, but if the exterior chars too quickly, move the skewers to indirect heat to finish cooking. Remove from the grill and let the skewers rest for 5 minutes before serving.
Transfer the cooked skewers to a platter and finish with a squeeze of lemon and some freshly chopped dill, if desired, for serving. Cut the grilled tomatoes into quarters and scatter around the chicken skewers along with the grilled onion and serrano peppers. Serve the skewers alongside the Shirazi salad, rice (if desired), and a scoop of the mint yogurt sauce.