Wash and drain red beans 2 to 3 times or until water runs clear. Top up with fresh water to cover beans. Soak for 4 to 8 hours.
Drain red beans. Transfer to a medium size saucepan. Top up with enough fresh water to cover red beans.
Place saucepan on the stove and bring water to a boil. Reduce heat to low and simmer for 1 hour. Top up with a little water when necessary.
After an hour, most of the water would have evaporated and beans should be very soft. Turn off stove and allow red beans to cool.
Using an immersion blender, pulse or blend red beans until smooth and fine.
Place saucepan back onto the stove over medium heat. Add sugar and salt. Stir to melt the sugar. Turn off stove and allow red bean paste to cool.
Transfer to air tight containers. Store in refrigerator for up to a week or in the freezer for up to a month.