Heat the olive oil in a large, heavy skillet, add the leek and garlic, and sweat over low heat until the leek is very soft, about 20 minutes. Add the paprika and cayenne and stir with a wooden spoon for about a minute. Add the tomato paste and stir for another minute. Pour in 1/2 cup/120 ml of the wine and the water. Bring to a gentle boil, reduce the heat to low, and simmer, covered, until the sauce is thick and dark, about 15 minutes. Season with salt and pepper.