Heat a large skillet and melt the butter. When it begins to brown ever so slightly around the edges, remove from the heat and add all of the tangerines slices. Stir to coat with the butter. Return to the heat and sprinkle with the sugar. Stir to blend.
Remove the skillet form the heat and add the orange liqueur. Remove from the heat and ignite with a long kitchen match. When the flames die down, transfer to a large serving dish or individual bowls. Serve with the vanilla ice cream.
Use extreme caution when igniting alcohol. Remove the pan from the heat source before adding the alcohol. Pour the alcohol into the pan and carefully ignite with a match or click lighter. Return the pan to the heat and gently swirl to reduce the flames.