Clean the tamarind. Remove the shells and stringy veins from the tamarind. Rinse to remove any loose pieces of shell.

Soak the tamarind. Add the cleaned tamarind and 2 cups of water to a saucepan. Let it soak for about 30 minutes to begin softening the pulp.

Prepare the seasonings. While the tamarind soaks, mash the garlic, Scotch bonnet pepper, and chadon beni together using a mortar and pestle.

Cook the tamarind. Place the saucepan over medium heat and bring to a low boil. Cook for about 20 minutes, stirring and pressing the tamarind as the pulp softens and separates from the seeds. Use a potato masher to help break up the pulp.

Remove the seeds. Remove the seeds and any remaining tough fibers using a spoon or sieve. Add a little more water if needed as the sauce cooks.

Season and sweeten. Add the mashed seasonings, brown sugar, and salt. Stir well and continue simmering until the sugar dissolves and the flavors come together.

Adjust the sauce. Taste and add more brown sugar as needed. If the sauce is too thick, add a little hot water. If it's too thin, continue simmering until it reaches your preferred consistency.

Cool and store. Remove from the heat and let the sauce cool completely. Transfer to an airtight container and refrigerate.