Wash capsicum and allow it to dry completely. Divide in two equal halves and remove its seeds. Now cut into long thin slices and place in a bowl. Add salt, cover and keep it under sunlight for 5-6 hours. With this juice will come out from the capsicum. If there is no sunlight, cover and leave it overnight in a room. Till morning juice will come out from the pieces of capsicum.
Strain the capsicum pieces.
Preheat mustard oil in a pan until smoky. Turn off the flame once oil is sufficiently hot and allow it cool a bit.
Now add asafoetida in oil and saute for while. Add capsicum chunks, turmeric, yellow mustard seeds, fennel powder, salt, red chilly powder and garam masala after sauteing asafoetida. Mix all ingredients really well. Also add vinegar into it. Stir and mix again.
Pickle is ready, take it out in a bowl. Allow the pickle to cool and store it in any container. Relish eating whenever you feel like. You can eat this pickle even now but it will taste more delectable after three days, as capsicum turn soft and spices get absorbed in it.
Container should be of plastic or glass. Thoroughly wash the containers with boiling water and dry under sunlight. Oven can also be used for drying containers.
Store the pickle in container and stir regularly for three days atleast once or twice in a day. With this spices will mix well in the pickle.
Use clean and dry spoon for taking out pickle from container. This increases the shelf life of pickle. Capsicum pickle can be consumed for up to 2-3 months.