Start by soaking wooden skewers in water for at least 30 minutes to prevent burning during grilling.
Prepare your vegetables: cut the bell peppers and zucchini into 2-inch chunks, and slice the red onion into thick rings. Place all the cut vegetables into a mixing bowl.
In a small bowl, whisk together olive oil, smoked paprika, minced garlic, and lemon zest to make a flavorful marinade.
Pour the marinade over the vegetables and gently toss to coat everything evenly. Let them sit for 15-20 minutes to absorb the flavors.
Preheat your grill or grill pan to medium-high heat, aiming for about 200°C (390°F). Lightly oil the grates to prevent sticking.
Thread the marinated vegetables onto the soaked skewers, alternating colors and types for a vibrant presentation. Leave a small space between each piece for even cooking.
Place the skewers on the hot grill, cooking for about 8-10 minutes. Turn them every 2-3 minutes to develop deep grill marks and smoky aroma, ensuring the vegetables are tender but still crisp.
Check for doneness: the vegetables should have deep charring on the edges, with the tomatoes slightly burst and onions caramelized and fragrant.
Remove the kababs from the grill and let them rest for 2-3 minutes. Brush with a little extra lemon juice or olive oil for added brightness.
Serve the vegetable kababs hot or at room temperature, garnished with fresh herbs if desired, and enjoy the smoky, crisp-tender bites.