Preheat oven to 375 degrees. On a rimmed baking sheet, toss potatoes with oil; roast 10 to 12 minutes. Flip; push to one side and add bread cubes. Continue to roast until potatoes are golden and tender and bread is crisp, 8 to 10 minutes more.

Reserve 1 tablespoon wine. In a small cast-iron pot, heat remaining wine with kirsch over low. Slowly add both cheeses, stirring in one direction until melted. Add nutmeg. In a small bowl, stir together lemon juice, cornstarch, and reserved wine. Slowly stir into pot; continue to cook over low heat, stirring, until mixture thickens and comes together, 4 to 5 minutes. Transfer to a fondue pot; keep warm. Serve with fennel, apple, salami, bread cubes and sticks, and potatoes.