Leg of Lamb Stuffed with Greens and Feta

Ingredients

1/3 cup olive oil, plus more for brushing

1 fennel bulb, trimmed (fronds and tender stalks reserved), halved and thinly sliced

1 1/2 cups thinly sliced scallions (white and most of the green parts)

1 tablespoon coarsely chopped garlic, plus 2 garlic cloves, quartered

1 1/2 cups coarsely chopped mixed greens (such as baby spinach, tender Swiss chard leaves, miner's lettuce, pea shoots, orache, green amaranth, outer leaves of escarole or romaine lettuce, and/or beet greens)

1 teaspoon fennel seeds, preferably freshly ground or crushed in a mortar

Freshly ground black pepper

1/4 cup chopped fresh mint

1 3 1/2-to-4 pound half leg of lamb (shank half), some fat left on, shank bone left in, hip end of bone removed (have the butcher do this, or see Note)

1/2 cup crumbled Feta cheese

Salt

1 teaspoon dried oregano, crumbled

1/2 cup dry white wine, plus more if needed

1/2 cup chopped fennel fronds plus tender stalks, or fresh dill