Butterflied Leg of Lamb with Rosemary and Garlic
1/4 cup olive oil
1/4 cup minced fresh rosemary
8 garlic cloves, minced
Kosher salt and ground black pepper
1 butterflied leg of lamb, 4 1/2 to 5 pounds
4 tablespoons butter, divided
3 tablespoons olive oil, divided
2 1/2 pounds golden yellow potatoes, peeled and halved
1 pound carrots, peeled and cut into large chunks
2 large onions, peeled, halved, and each half quartered
2 pounds of asparagus, tough end snapped off
1 teaspoon finely grated lemon zest; lemon cut into eighths
2 bags (2 pounds) frozen peas
1/4 cup chopped fresh mint
For the lamb, mix oil, rosemary, garlic, 1 tablespoon of salt, and 1 1/2 teaspoons pepper in a small bowl; rub mixture on both sides of lamb. (Can be set aside at room temperature up to 2 hours.)
When ready to roast, set a large heavy-duty roasting pan over 2 burners at medium-high heat. When pan is hot add lamb; cook, turning only once, until well browned on both sides, 6 to 8 minutes total. Transfer lamb to a large rack; do not wash roasting pan.
For the vegetables, adjust oven racks to lowest and upper positions and heat oven to 400 degrees. Mix 2 tablespoons melted butter with 2 tablespoons of the oil. Bring potatoes with water to cover to boil in a small pot. Reduce heat to medium-low, cover and cook until potato surface is just tender, about 5 minutes. Drain water, cover, and shake pot to give potatoes a “ fluffy” surface; turn into roasting pan, along with carrots and potatoes; drizzle with butter mixture along with a generous sprinkling of salt and pepper; shake roasting pan to coat. Set lamb on rack over roasting pan; roast until a meat thermometer inserted into the thickest part of the roast registers 135 for medium-rare and 140 degrees for medium, about 30 minutes. Remove rack and lamb from roasting pan; let lamb rest. Return roasting pan of vegetables to oven and increase temperature to 450 degrees.
While lamb roasts, toss asparagus with remaining 1 tablespoon of oil and a generous sprinkling of salt and pepper on a large rimmed baking pan. Place peas, mint, remaining 2 tablespoons of butter, and a light sprinkling of salt and pepper in a large microwave-safe bowl; cover with plastic wrap.
While lamb rests, roast asparagus on upper oven rack until bright green and tender-crisp (tossing with lemon zest post oven) and potatoes, carrots, and onions until nicely browned, about 10 minutes longer. Microwave peas on high power until very hot, 8 to 10 minutes.
When ready to serve, slice as much lamb as you think you’ll eat. Arrange all on a large platter. Garnish with lemons for squeezing on lamb. Serve.