Remove the skin from the chicken and cut 3-4 slashes into the flesh of each piece.
Heat a little oil in the base of a heavy frying pan and add the mustard, fennel and cumin seeds, allow them to pop then stir in the tumeric, cinnamon and flour.
Take care not to burn the spices, this could happen very quickly.
Add the garlic, green/red pepper and onion to the spice mixture and cook for a few minutes stirring all the time.
Add the chicken and tomatoes, stir to mix, cover and cook gently for 15 minutes.
Meanwhile, cook the peeled and chopped potatoes in boiling water for 5 minutes, then drain them.
Add the potatoes to the chicken and stir to combine, continue to simmer gently for 20-25 minutes until the chicken is completely cooked and tender.
Add the peas and allow to warm through for a few minutes.
Serve hot with Naan Bread and/or rice and pickles.