You can put fruit on the grill, ears of corn, thin spears of asparagus, pizza (see Page 5), and avocados. We were intrigued with this recipe from Aldi, an international supermarket chain with stores in Medford, Milford, Leominster, and Worcester. To grill avocados, choose fruits that are firmer than ones you would use for making guacamole. Halve and pit them, and brush with an olive oil and lemon dressing. Then grill on both sides to give the halves a smoky flavor, and top with a grilled salad of Roma tomatoes (they have less liquid), onion, and red bell peppers tossed with a lemony dressing. Garnish with crumbles of salty feta.