Rub the inside of a small enameled cast-iron saucepan or stovetop fondue pot with the cut sides of the garlic clove; discard the garlic. Add the wine, lemon juice and mustard to the saucepan and bring just to simmer over medium heat.
In a medium bowl, mix the gruyere, emmentaler and gouda with the cornstarch. Gradually stir the cheese mixture into the saucepan in handfuls, stirring until the fondue is creamy and smooth, about 5 minutes; do not overcook. Season the fondue with salt, then sprinkle generously with paprika; serve right away with bread, sliced apples, salami and raw vegetables for dipping.