Adjust rack to top position and preheat oven to 425 degrees. Wash and dry all produce. Drain and rinse chickpeas; pat very dry with paper towels. Core, deseed, and dice bell pepper into ½-inch pieces.

Toss bell pepper and chickpeas on a baking sheet with a large drizzle of olive oil, 1 tsp harissa powder (2 tsp for 4 servings), and salt. (For 4, divide between 2 baking sheets.) Roast on top rack until bell pepper is softened and chickpeas are lightly browned, 18-20 minutes. TIP: It’s natural for chickpeas to pop a bit while roasting!

Meanwhile, in a small pot, combine bulgur, 1 cup water, ½ tsp harissa powder, and ½ tsp salt. (For 4 servings, combine bulgur with 2 cups water, 1 tsp harissa powder, and 1 tsp salt.) Bring to a boil, then cover and reduce to a low simmer. Cook until water has absorbed and bulgur is tender, 12-15 minutes. Turn off heat; keep covered until ready to serve.

While bulgur cooks, trim and finely dice cucumber. Finely dice tomato. Trim and thinly slice scallions, separating whites from greens; mince whites. Pick dill fronds from stems; discard stems and mince fronds. Zest and halve lemon. In a small bowl, whisk together sour cream, 2 TBSP feta (¼ cup for 4 servings), and 1 TBSP olive oil. Add water 1 tsp at a time until mixture reaches a drizzling consistency. Season with salt and pepper.

Squeeze juice from 1 lemon half (whole lemon for 4 servings) into a large bowl. Whisk in 2 TBSP olive oil (¼ cup for 4), lemon zest, and ¼ tsp salt (½ tsp for 4). If necessary, drain any excess water from bulgur; stir into bowl along with cucumber, tomato, scallion whites, dill (to taste; start with half and add more from there), and remaining feta. Taste and season with salt and pepper.

Divide tabbouleh between bowls or plates. Top with roasted bell pepper and chickpeas. Drizzle with feta dressing and sprinkle with scallion greens. Cut remaining lemon into wedges and serve on the side.