Separate lettuce leaves; rinse lightly and dry. Heat oil in a large skillet over medium heat, and sauté onion, ginger, and garlic 3 – 5 minutes. Add pork and cook until done, about 5 – 7 minutes. Drain excess fat from pan. Add lime juice, peanuts, cilantro, chili, and ¼ teaspoon salt, and cook an additional 2 minutes. Transfer to a bowl, and serve filling on top of lettuce leaves.
Clean silks from corn, leaving husks intact. Replace husks, and grill corn over medium heat 5 – 7 minutes. Rub warm corn with butter; sprinkle with chili powder, lime juice, and ⅛ teaspoon salt.