Begin filling your rumtopf crock in midsummer, when perky strawberries first give off their perfume. Carry on with raspberries, and later apricots, layering the jar with more rum and sugar at every addition. As the weather begins to cool and plums reach their peak, stir them in. Rumtopf can and should be consumed year-round, but it's traditionally a holiday thing. So when sweater weather arrives, you're close. In go apples and pears, and by December you have a dark, lustrous elixir to sip from sherry glasses and rum-soaked fruit to spoon over spice cake—a whole sweet year concentrated into a single swig.