In a large saucepan heat the oil over medium high heat. Add the onions and cook until they begin to caramelize, about 6 minutes. Add the garlic and cook 2 minutes, then add the tomatoes and cook, stirring often, until they start to release some of their moisture, about 5 minutes. Add the huckleberries to the pot, reduce the heat to medium low, and cook for 5 minutes. Add the remaining ingredients, except the gin, and stew over medium heat until the mixture is thick and has reduced in volume by nearly 3/4, about 15 to 20 minutes. Stir in the gin and cook an additional 3 minutes.
Strain the ketchup into a small bowl and allow to cool before serving.