Preheat the oven to 400° F.

Place the sliced cauliflower, red pepper, onions, and garbanzo beans in a large bowl.

In a small bowl, whisk together the olive oil, lemon juice, and zest, minced garlic, cumin, coriander, paprika, onion powder, salt, and pepper.  Pour the marinade over the veggies and toss until well coated.

Spread the veggies out on 2 sheet pans so they have room to caramelize and not steam while roasting.  Roast in the oven for 30 to 35 minutes until the veggies are tender and slightly caramelized.

Meanwhile, prepare the couscous.  In a small saucepan with a lid, add the water or broth, a pinch of salt, and olive oil to a boil.  Stir in the couscous, top with a lid and remove from the heat.    Let the couscous sit for about 5 minutes to absorb all the liquid.  Fluff the couscous with a fork, then add the fresh herbs and stir until incorporated.

Lastly, prepare the lemon tahini sauce.  In a small bowl, whisk together the tahini,  lemon juice, warm water, and cumin.  If the mixture is too thick, add a little more warm water in teaspoon increments to thin it out so that it can be drizzled from a spoon over the veggie shawarmas.

Assemble the bowls by placing some herbed couscous in a bowl and topping with the roasted veggies and chickpeas and any additional garnishes like thinly sliced cucumbers, cherry tomatoes, olives, feta cheese, and a drizzle of the lemon tahini sauce.  Serve with toasted pita bread if desired.