In a small bowl, combine olive oil, minced garlic, chopped rosemary, salt, and black pepper. Rub this mixture all over the rack of lamb. Cover and let marinate in the refrigerator for at least 1 hour.

Prepare Quinoa

Rinse the quinoa under cold water. In a saucepan, bring vegetable broth to a boil. Add quinoa, reduce heat to low, cover, and simmer for about 15 minutes or until quinoa is fluffy and the liquid is absorbed. Fluff with a fork and stir in chopped parsley.

Roast Vegetables

Preheat the oven to 425°F (220°C). Chop the bell peppers, zucchini, and red onion into bite-sized pieces. Toss the vegetables with olive oil, salt, and pepper on a baking sheet. Roast for 20-25 minutes until tender and slightly caramelized.

Grill the Lamb

Preheat the grill to medium-high heat. Remove the lamb from the marinade and grill for about 15-20 minutes, turning occasionally, until the internal temperature reaches 135°F (57°C) for medium-rare. Let rest for 5 minutes before slicing.

Serve

Slice the rack of lamb and serve it with quinoa, roasted vegetables, and a generous drizzle of romesco sauce.