To prepare Fish Ambat Tikhat, grind together coconut, coriander leaves, garlic, ginger, coriander seeds, cumin seeds, green chilies, vinegar to a fine paste using little water.
In a heavy bottom pan, heat oil. Add onions and fry until it starts picking up the light brown color. Do not over brown the onions.
Add the ground masala paste and cook on high heat for 3 to 5 minutes.
Add turmeric, red chili powder, tamarind, tirphala water, salt and mix well. Cook until the spices start leaving oil.
Add required amount of warm water and bring it to the boil. Depending upon the thickness of the gravy preferred, the amount of water can be increased or decreased, but traditionally the gravy is slightly thin.
Add fish slices and kokum water. Cover and simmer until fish is cooked through.
Dish out and garnish with green coriander leaves and serve hot with steamed rice.