In a large zip-top bag or bowl, combine the chicken chunks, 3 tablespoons olive oil, balsamic vinegar, smoked paprika, chopped oregano, chopped shallot, minced garlic, lemon zest, lemon juice, crushed red pepper flakes, and a large pinch of kosher salt and some black pepper; seal and marinate at room temperature 15 minutes or refrigerate up to overnight.
While the chicken marinates, make the mint oil: heat 1/4 cup olive oil in a small skillet over medium heat until shimmering, remove from heat, stir in the chopped mint so it sizzles, then set aside to cool.
Make the yogurt sauce by stirring the Greek yogurt, chopped basil or parsley, juice of 1 lemon, halved and seeded jalapeño, 1 teaspoon cumin, and a pinch of salt together in a medium bowl until smooth.
Prepare your grill, grill pan, or skillet over medium-high heat. Thread marinated chicken onto skewers if using, or leave loose for pan-roasting; you can also roast the chicken in a 400°F (200°C) oven for 20–30 minutes.
Grill or cook the chicken, turning occasionally, until lightly charred and cooked through, about 10–12 minutes total depending on piece size (internal temperature 165°F / 74°C).
To assemble bowls, spread some yogurt sauce on each plate and drizzle with the mint oil. Divide the cooked orzo or couscous among bowls, then top with roasted red pepper, feta, sliced avocado, Persian cucumbers, olives, and the cooked chicken. Garnish with basil and serve.