Honey-Vinegar Leg of Lamb with Fennel and Carrots

INGREDIENTS

• 1/2 cup red wine vinegar
• 2 garlic cloves, chopped
• Kosher salt, freshly ground pepper
• 1/3 cup honey
• 16 small carrots (about 2 pounds), unpeeled, halved lengthwise if large
• 1 cup fresh flat-leaf parsley leaves
• 1 7–9 pound bone-in leg of lamb, tied
• 4 fennel bulbs, sliced 1/2" thick
• 1/2 cup fennel fronds plus more for serving
• 1 tablespoon fennel seeds, crushed
• 1/2 cup olive oil, divided