1. Remove lamb from netting and unroll. Place the lamb in large bowl and season with 1½ teaspoons salt and pepper. Coat with 2 tablespoons oil, ½ cup wine, juice of 1 lemon and fennel fronds. Cover and refrigerate for 2 hours to marinate.
2. Transfer lamb to cutting board; roll back together and tie up tightly with twine to ensure even cooking. Poke 16 holes large enough to stud with garlic, then stuff holes with the garlic.
3. In heavy-gauge roasting pan, add fennel, remaining lemons, cut side down and drained potatoes. Drizzle with the remaining 2 tablespoons oil and season with remaining 1½ teaspoons salt. Place the lamb on top of the vegetables. Roast in convection oven at 350°F for 30 minutes. Add the tomatoes on the vine; reduce oven to 325°F. Roast 20-25 minutes longer or until internal temperature of lamb reaches 145°F. Watch carefully and remove tomatoes as they start to blister. Keep warm.
4. Skim excess fat from roasting pan. With pan over medium-high heat, add olives and deglaze with remaining 1 cup wine, scraping bottom of pan to release fond. Cook until slightly reduced. Add stock and reduce an additional 6 minutes. Squeeze juice from 2 roasted lemon halves into pan and swirl in butter. Keep warm.
For the Charred Broccolini
1. Preheat char grill over medium-high heat; toss broccolini with a ½
tablespoon oil and 1 teaspoon salt. Grill broccolini about 1½-2 minutes per side.
Remove from grill and reserve.
2. Finish broccolini by preheating a heavy-gauge sauté pan over medium-high heat until hot. Add the remaining 3 tablespoons oil and garlic; cook about 1 minute stirring so not to burn. Stir in crushed red pepper, and then the charred broccolini. Reduce heat to medium and cook 3-4 minutes or just until tender-crisp, stirring often. Remove from heat; add lemon juice and remaining 1 teaspoon salt.
3. Cut away twine from lamb and slice. Transfer lamb to platter and drizzle with some of the pan sauce. Serve with vegetables, broccolini and remaining pan sauce.