Why is milk so good to use pre-cook fish fillets prior breading and baking?

You're actually not using milk to pre-cook fish fillets prior to breading and baking. Milk is used for marination or brining which is a different process than pre-cooking.

Here's why milk is a good choice for preparing fish before breading and baking:

* Moisture: Milk adds moisture to the fish, keeping it tender and juicy during baking.

* Flavor: Milk adds a subtle creaminess and richness to the fish.

* Tenderness: The lactic acid in milk helps break down some of the proteins in the fish, resulting in a more tender texture.

* Crusting: Milk helps the breading adhere better to the fish, resulting in a crispy, flavorful crust.

Pre-cooking would involve actually cooking the fish before breading and baking, typically using a method like pan-frying or grilling. This would generally be done for fish that is already quite thin or tender and needs to be cooked through before being baked.

So, to summarize: Milk is used to marinate fish before breading and baking, not pre-cook it. This helps to improve the fish's texture, flavor, and crusting.