Step 1

Adjust rack to top and middle positions and preheat oven to 450 degrees. Wash and dry all produce. Trim and quarter zucchini lengthwise; cut crosswise into 1-inch-thick pieces. Core, deseed, and dice bell pepper into 1-inch pieces. Halve, peel, and slice shallot into ½-inch-thick wedges. Trim and thinly slice scallions, separating whites from greens. Zest and quarter lemon.

Step 2

Toss zucchini, bell pepper, and shallot on a baking sheet with a drizzle of olive oil, Tunisian Spice, salt, and pepper. Roast on top rack until browned and tender, 18-20 minutes.

Step 3

Meanwhile, slice each pita into 6 triangles; rub all over with a large drizzle of olive oil until evenly coated. Spread out on a second baking sheet. Sprinkle on both sides with salt and half the garlic powder (all for 4 servings). Bake on middle rack until crisp and browned at edges, 10-12 minutes.

Step 4

Heat a drizzle of olive oil in a small pot over medium-high heat. Add scallion whites and cook until slightly softened, 1 minute. Add ¾ cup water (1½ cups for 4 servings), stock concentrate, and a big pinch of salt. Bring to a boil, then stir in couscous. Immediately cover and remove pot from heat; let sit until ready to serve.

Step 5

In a small bowl, combine yogurt, sour cream, feta, a drizzle of olive oil, and a squeeze of lemon juice to taste. Season with salt and pepper.

Step 6

Fluff couscous with a fork; stir in lemon zest and season with salt and pepper. Divide between plates; top with roasted veggies and sauce. Sprinkle with scallion greens. Serve with pita chips and any remaining lemon wedges on the side.