Wash the okra, top and tail, and cut into approximately 1 cm pieces (or leave whole after topping and tailing if preferred). Fry mustard, coriander and fenugreek seeds in mustard oil for 2-3 minutes (cover the pan or the mustard seeds will leap out all over the kitchen!). Add garlic, onion and ginger; fry gently for about 10 minutes more. Make the ground spices into a paste with a little water, add to the pan and fry for a further 10 minutes. Add okra, tomatoes, green pepper and chiles. Cover and simmer very slowly until the okra is tender but not sloppy (about 15-20 minutes). Serves 3-4 as a main course, 5-6 as a side vegetable.