Rub the inside of a medium saucepan with the cut clove of garlic. Discard garlic clove.
Add wine and lemon juice (if using) to the pan. Heat until steaming.
Toss grated cheese with the cornstarch. Add a little of the cheese at a time to the warm wine mixture, stirring until each addition is dissolved before adding more.
Heat the cheese until thick and smooth, over medium heat. Fondue is done when the cheese runs smoothly off the spoon. (Or forms a film over the center of a spoon with a hole in it.)
Transfer fondue to a fondue pot, and light the burner beneath the pot.
Enjoy with your choice of dippers and plenty of white wine.
Notes
*We like lightly blanched broccoli, raw cauliflower, mushrooms, sweet apples, firm pears, grapes, summer sausage, boiled red potatoes, and pickles.