Follow these steps to create delicious and perfectly grilled veggie kebabs:

1. Prepare the Marinade: In a small bowl or liquid measuring cup, whisk together the olive oil, lemon juice, balsamic vinegar (if using), minced garlic, Italian herbs, smoked paprika (if using), salt, pepper, maple syrup/agave (if using), and red pepper flakes (if using). Taste and adjust seasonings if necessary. Set aside. This marinade is the heart of the recipe, infusing the vegetables with incredible flavor.
2. Prepare the Vegetables (and Tofu/Halloumi if using):
   • Wash all vegetables thoroughly.
   • Bell Peppers: Remove seeds and membranes, then chop into 1 to 1.5-inch (2.5-3.8 cm) uniform pieces. Uniformity is key for even cooking.
   • Zucchini: Trim ends and cut into 1/2 to 3/4-inch (1.3-1.9 cm) thick rounds or half-moons if the zucchini is very large.
   • Red Onion: Peel and cut into 1 to 1.5-inch wedges, ensuring each piece has a bit of the root end to help it hold together on the skewer.
   • Mushrooms: If using button mushrooms, you can leave them whole or halve them if large. Cremini mushrooms can also be kept whole or halved. Gently wipe them clean with a damp paper towel rather than washing, as they absorb water.
   • Cherry/Grape Tomatoes: Leave whole.
   • Tofu (if using): If you haven’t already, press the tofu for at least 30 minutes to remove excess water. Cut into 1-inch cubes.
   • Halloumi (if using): Cut into 1-inch cubes.
3. Marinate the Vegetables: Place all the chopped vegetables (and tofu/halloumi, if using) into a large bowl or a large resealable plastic bag. Pour the prepared marinade over the vegetables. Toss gently but thoroughly to ensure everything is evenly coated.
4. Chill (Make-Ahead Step): Cover the bowl or seal the bag and refrigerate for at least 1 hour, or ideally for 4-6 hours, or even overnight (up to 24 hours). The longer they marinate, the more flavorful they will be. If marinating for more than a couple of hours, give them a stir occasionally. This marinating time is crucial for the “make-ahead” aspect and significantly boosts the flavor.
5. Soak Skewers (if using wooden): About 30 minutes before you’re ready to assemble and grill, if you are using wooden skewers, soak them in water. This helps prevent them from burning on the grill.
6. Assemble the Kebabs:
   • Remove the marinated vegetables from the refrigerator.
   • Thread the vegetables (and tofu/halloumi) onto the skewers in an alternating pattern, creating a colorful and appealing arrangement. Try to pack them snugly but not too tightly, as this can prevent even cooking.
   • Leave a little space at each end of the skewer for easier handling.
   • Reserve any leftover marinade from the bowl/bag for basting, if desired.
7. Cook the Kebabs: You have several options for cooking:
   • Grilling (Recommended):
     • Preheat your grill to medium-high heat (around 375-450°F or 190-230°C).
     • Clean and lightly oil the grill grates to prevent sticking.
     • Place the kebabs directly on the preheated grill.
     • Grill for about 10-15 minutes, turning every 3-4 minutes, until the vegetables are tender-crisp and have nice char marks. Baste with reserved marinade during the first half of grilling, if desired (ensure any marinade that touched raw tofu, if used and not pre-cooked, is boiled before basting or discarded).
   • Oven Roasting:
     • Preheat your oven to 400°F (200°C).
     • Line a large baking sheet with parchment paper for easy cleanup.
     • Arrange the kebabs in a single layer on the baking sheet, ensuring they don’t overcrowd the pan (use two sheets if necessary).
     • Roast for 15-25 minutes, turning halfway through, until the vegetables are tender and slightly caramelized. You can broil them for the last 1-2 minutes for extra char, watching carefully to prevent burning.
   • Pan-Frying/Griddle:
     • Heat a large griddle pan or skillet over medium-high heat with a little olive oil.
     • Place kebabs in the hot pan (you may need to cook in batches).
     • Cook for 10-15 minutes, turning occasionally, until vegetables are tender and charred in spots.
8. Rest and Serve: Once cooked, remove the kebabs from the heat, let them rest for a few minutes, and then serve warm.