In a clean, dry pan, toast black sesame seeds over low heat. Move them around with a spatula constantly to heat evenly.
When the seeds become plump and can be crushed easily between fingertips, remove them from the heat (It took me about 6 minutes).
Grind
Transfer the toasted seeds to a food processor, a blender, or a spice grinder. Run the machine in full power to grind them. Take breaks periodically to avoid overheating the machine. Also, use a flexible spatula to scrape off any seeds sticking to the side.
Once the seeds release their natural oil and become a semi-solid, smooth paste, transfer it to a bowl.
Flavor
Use honey if you prefer a firm paste that holds its shape easily. Pour it over the paste, then fold with a spatula to combine thoroughly.
Use white or brown sugar if you prefer a runnier paste. Add it little by little. Taste and adjust its quantity as needed.
Optionally, add softened butter (or coconut oil) to the paste to enrich its flavor and increase its fluidity in hot food (see note 2).
Store
Store the paste in a sterilized, airtight container. Keep it in the fridge for a month or in the freezer for 6 months.
Notes
1. Apart from honey and sugar, you may also use golden syrup, maple syrup, brown rice syrup, etc. to sweeten the paste. 2. If you plan to use black sesame paste as a filling for hot food, I recommend you consider adding butter or coconut oil. This helps to create a lava-like consistency when served warm.