Soak the beans in water for 1 hour (use filtered water if possible).
Drain off the water, and dry roast the beans in a pan (keep roasting until almost all the moisture is gone. The skins on the beans should pop).
Line a heatproof dish with paper towels. Put the roasted beans on the paper, and microwave for 3 minutes.
Take the beans out and mix them up, and microwave for another 3 minutes. Let them cool down here. Taste one, and if it's nice and crunchy the beans are done. If they are still moist, keep microwaving in short increments while testing them.
Store in a jar.
Addendum: Pour boiling water over 15 roasted beans, and leave to steep for 2 to 3 minutes to make black bean tea. I like to make 2 cups of tea from the same beans, then eat the softened beans that are left over (Maybe it's just me?).
This is roasted black beans and black rice cooked with regular white rice. I added a bit more water than usual, and soaked the rice with the beans and black rice for more than 30 minutes before cooking.
Cook with the regular rice cooker setting. The rice turned purple like this. The beans become plump and really aromatic.
To make black bean tea in the microwave: put 15 roasted beans in a cup, add water, and microwave for 1 minute 40 seconds at 600 W. Leave to steep for a while.
I made porridge with the black bean rice, and kneaded it in to bread dough.
This is roasted black beans and zakkoku-mai (mixed grain mix) with regular rice.
This is the same rice from Step 11 turned into porridge the next day.
Story Behind this Recipe
I adapted and improved on the instructions for roasting beans that I saw online. You can eat these as-is, make black bean tea from them, cook them with rice, or in many other ways.
Just soak the beans for 1 hour only. If you soak them longer, it will be very hard to make them crunchy.