INGREDIENTS
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1/2 cup (1 stick) unsalted butter
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1 large or 2 medium-size yellow onions, chopped
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1 quart home-canned tomatoes or one 28-ounce can imported Italian whole or chopped plum tomatoes, with their juice
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1/2 cup dry vermouth or dry white wine
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1 tablespoon sugar
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1 heaping teaspoon dried tarragon
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Kosher or sea salt to taste
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Cold sour cream for serving