How to Make It
In a blender, combine the chipotle chiles with the molasses, balsamic vinegar, dark brown sugar and 1/4 cup of the water. Blend until the mixture is smooth.
Strain the sweet chipotle puree through a fine strainer into a small saucepan, pressing on the solids with a spatula to extract as much of the puree as possible.
Simmer the chipotle sauce over moderately low heat, stirring frequently with a heatproof rubber spatula, until it is very thick, pasty and reduced to 3/4 cup, about 20 minutes. Remove the salsa from the heat. Stir in the soy sauce and remaining 1/4 cup of water. Serve the salsa negra hot or at room temperature.