Today, EVERYDAY FOOD is all about planning ahead. Sarah starts with tender roast beef with peppers, onions and potatoes. Margot uses the extra roast beef for a healthy and colorful beef mango wrap, a fantastic lunch sandwich. For something more substantial for dinner, the wraps are served with a bowl of black bean relish. With the extra mangoes, Emma prepares a quick dessert: mango brown betty. Lucinda makes a spice-rubbed turkey breast with sweet potatoes that's a fast and hearty dinner the whole family will enjoy. Sauteed escarole and garlic complete the meal. Allie uses the extra turkey for two salads: a fresh, crisp spinach salad and a pasta salad tossed with mushrooms and dried cranberries.