Rub salt to the fish pieces and keep aside, then rinse.
Heat oil in a pan, add the fenugreek seeds and saute till dark brown. Then remove the seeds from the oil.
Add onions in the same oil and saute till translucent.
Add ginger garlic paste and saute.
Add finely chopped tomatoes, chili powder, turmeric, coriander powder, cumin powder and let it cook till the mixture turns into a sauce like consistency.Stir in the fenugreek leaves.
Add the fish pieces,salt, little water(if desired) and let it cook on a slow flame.
Squeeze in some lemon juice before serving.