Cheddar Beer Fondue III

In a bowl combine Monterey Jack, Gruyere, sharp Cheddar and flour; mix well to coat cheese with flour. Set aside. In a large saucepan, bring beer to a simmer over medium heat. Reduce heat to medium low. Add cheese-flour mixture by handfuls to saucepan, stirring constantly after each addition with a wooden spoon in a figure-eight motion until cheese is melted. When cheese is nearly all melted, stir in dry mustard, mixing well. Transfer to fondue pot and serve immediately.