Bring broth to a simmer in a medium saucepan (do not boil). Keep warm over low heat.
Heat oil in a large saucepan over medium heat. Add leek; sauté 4 minutes or until tender. Add rice; cook 1 minute, stirring constantly. Stir in wine; cook 1 minute or until the liquid is nearly absorbed, stirring constantly. Reduce heat to low; stir in greens. Add broth, 1/2 cup at a time, stirring constantly until each portion of broth is absorbed before adding the next portion (about 25 minutes). Stir in cheese and pepper. Serve with lemon wedges.