This fondue is great because it's made with ingredients that you can always have on hand. It's also good when made with beer, instead of wine. Try Brennan's Cellars Pilsner.
Cook tomatoes and garlic in butter in a 4-quart heavy saucepan over moderately low heat, stirring occasionally, until most of liquid is evaporated, about 5 minutes. Stir together wine and cornstarch in a small bowl, then stir in tomatoes and simmer gently, stirring, 1 minute. Discard garlic. Add cheddar by handfuls, stirring until completely melted.
Serve in a fondue pot over a flame