Ingredients :
2 white fish fillets
3 tbsp oil
1/2 tsp salt
1/2 tsp turmeric powder
2 spring spring onions, chopped finely
1 tbsp butter
1 tbsp cornflour
3 tbsp dijon mustard
1 cup milk
Salt as per taste 

Method 

1-Clean the fillets and make into serving pieces. Marinate with salt and turmeric powder. Keep aside for 1/2 hour 
2-Heat oil in a pan, put the fish pieces and let it cook, stirring occasionally, cook till fish flakes easily 
3-Remove and drain the fish fillets, arrange in the casserole 
4-Heat butter in a pan, add cornflour and stir continuously till smooth ,add milk and stir & cook till it thickens.
4-Add salt and mustard and cook for 3-4 minutes & remove from fire. Pour the mustard sauce over the fillets 
5-Garnish with with chopped spring onions