Place beans in a large pot. Cover with water. Bring to boil. Simmer for about an hour or until the beans are tender. Drain.

Reserve 1 and ½ cups water.

Alternatively, you can cook dried beans in a pressure cooker. Place beans in the cooker and cover with water. Cook until 3 whistles.

Heat oil in a small frying pan over low heat. Fry, stirring, for 2-3 minutes or until coconut starts to brown.

Add fennel seeds, ground turmeric, ground coriander and red chili powder. Fry, stirring, for 1 minute. Remove from heat. Leave to cool completely.

Once cooled, place it in a food processor. Add a little water, and grind to a smooth paste. Set aside.

Place coconut paste and cooked beans in a large saucepan over medium-high heat.

Add cucumber. Pour in enough reserved water to make a thick sauce. Season with salt.

Bring to a boil. Reduce heat and simmer for 2-3 minutes or until the cucumbers are tender.

Heat oil in a small frying pan over medium heat. Add mustard seeds. Allow to splutter.

Add onions, dried red chilies and curry leaves. Sauté, stirring, for about 2-3 minutes or until the onions are browned.

Pour tempered spices into the curry. Stir to combine.