Combine vinegar, ginger and garlic in a blender and process for one minute. In a heavy-bottomed medium saucepan, combine the blender contents and the remaining ingredients. Add just enough water to cover. Bring to a boil, then reduce to a simmer. Cook, stirring occasionally, until the mixture is very thick, 30-45 minutes. Taste for seasonings and add more salt or cayenne to your taste. Pour onto a cookie sheet and cool to room temperature. Store covered in the refrigerator for up to one month.

Assembly:
Place 1 ounce of chilled chutney in the bottom of each of four chilled martini glasses. Top with two ounces of crabmeat and one ounce of cranberry juice. Stir the vodka into the crème frâiche and spoon sparingly on top of the crabmeat. Garnish with the chervil sprigs and serve.