Heat the olive oil in a wide Dutch oven or deep lidded sauté pan over medium-high heat. Add the tofu in a single layer, season with 1/4 teaspoon salt, and cook for 5 to 7 minutes, turning occasionally, until lightly browned on several sides. Transfer the tofu to a plate.

In the same pot, add the zucchini, bell pepper, and red onion. Cook over medium-high heat for 5 to 6 minutes, stirring only occasionally, until the vegetables pick up browned edges and soften slightly. Transfer them to the plate with the tofu.

Reduce the heat to medium. Add the garlic, tomato paste, harissa, cumin, coriander, and 1 tablespoon water to the same pot. Stir for 1 minute, scraping up browned bits, until the paste darkens and smells fragrant.

Add the rinsed quinoa and chickpeas to the pot and stir for 1 minute to coat them in the spiced tomato mixture.

Pour in the vegetable broth, then add the cherry tomatoes, black pepper, and remaining 3/4 teaspoon salt. Bring to a simmer, scraping the bottom of the pot once more.

Return the tofu to the pot and fold it in gently. Cover, reduce the heat to low, and cook for 15 to 18 minutes, until the quinoa is tender and most of the liquid has been absorbed.

Turn off the heat. Scatter the pan-roasted zucchini, pepper, and onion over the quinoa mixture, cover again, and let the pot rest for 5 minutes so the vegetables warm through without becoming mushy.

Drizzle the tahini and lemon juice over the pot, then gently fold just enough to create a creamy, streaky sauce. Top with olives and fresh herbs, and serve with lemon wedges.