Tip 1: Add a little potash and boil till it starts frying like stew. Don't allow it to burn, just make sure it doesn't foam and you leave it open.
Tip 2: Add a little palm oil and onions. Then place it on your cooker with a medium heat.
Tip 3: Maggi and Crayfish, then a little potash. Also allow to fry slowly. Add oil and pepper. Although it won't regain it's original flavour, it will taste better.
Tip 4: Bring to boil then just put some baking powder (not baking soda), stir and all the sour will come up (keep stirring till it finish foaming) then taste and adjust the seasoning. Works wonders and its healthier than potash plus it doesn't change food colour.
Tip 6: If all don't work for you, pick out the meat, fish, etc, you used in cooking, wash with hot water, then use to prepare another food. At least you haven't lost all your expenses.
Washing the meat or fish with hot water helps in killing the bacterial and enzymic reactions that caused the souring. That way it's safe to use the washed stuff for another hot meal.