Like peppers, tomatoes can be frozen raw. Frozen tomatoes are best used in cooked foods such as soups, sauces and stews as they become mushy when they're thawed. The National Center for Home Food Preservation offers these guidelines for freezing tomatoes:
Select firm, ripe tomatoes with deep red color. Wash and dip in boiling water for 30 seconds to loosen skins. Core and peel. Freeze whole or in pieces. Pack into containers, leaving l-inch headspace. Seal and freeze. Use only for cooking or seasoning as tomatoes will not be solid when thawed.
TIP: Dip just a few tomatoes at a time into the boiling water or the water temperature may be lowered too much to remove the skins without overheating the tomatoes. Place hot tomatoes in a colander and rinse under cold water to make them easier to handle. A knife with a serrated edge works best for cutting tomatoes.