Slow Roasted Lamb Shoulder with Homemade Harissa

Name: Slow Roasted Lamb Shoulder with Homemade Harissa
Ingredients: 1/4 teaspoon caraway seeds; 1/4 teaspoon coriander seeds; 1/4 teaspoon cumin seeds; 2 ounces ancho chiles (about 4), stemmed and seeded; 1 tablespoon smoked sweet paprika; 1 tablespoon lemon juice; 3 large garlic cloves, 1 clove mashed to a paste; 1/4 cup extra-virgin olive oil, divided; 1 tablespoon k osher salt, plus more for seasoning the yogurt sauce to taste; 1 (3-pound) lamb shoulder roast on the bone; 1 cup plain Greek yogurt; 2 tablespoons chopped cilantro; Freshly ground black pepper; Lettuce leaves, for serving; Warm naan, for serving