Fondue is traditionally prepared in a pot called a 'caquelon'. Continuous stirring and temperature control are key to achieving the correct consistency and emulsion.
The most common mix is the 'moitié-moitié' (half-half) of Gruyère and Vacherin, or Gruyère and Emmentaler. Use only high-quality, dry white wine (e.g., Sauvignon Blanc or Chardonnay).
Use pieces of day-old bread with a crust for dipping so they don't disintegrate. Try small boiled potatoes, pickled onions, or cornichons as well.
Thoroughly rub the inside of the fondue pot (caquelon) or heavy-bottomed pot with the cut garlic clove (discard the garlic or chop and add it for a stronger flavour).
Toss the grated cheese with the cornstarch. The starch prevents the fondue from separating or becoming grainy.
Pour the white wine and lemon juice into the pot. Heat over moderate heat (just below boiling point).
Gradually, by small handfuls, add the cheese and cornstarch mixture. Stir continuously with a wooden spoon in a figure-eight motion. The cheeses must melt slowly.
Once the fondue is smooth, glossy, and creamy (about 10-15 minutes), remove it from the stove.
In a small bowl, mix the Kirsch with a little bit of the fondue, and stir this mixture back into the main pot. Add a pinch of nutmeg and black pepper.
Transfer the pot to a burner (rechaud) on the table. The flame should be very low, only keeping the fondue hot, not bubbling.
Skewer bread pieces onto long forks, dip into the cheese, and twist to prevent dripping. Serve immediately.