The exact amount of liquid to make depends on how much fish you're cooking, but make enough to pour over the fish fillet pieces, leaving some in the pan. The fish doesn't need to be swimming in sauce.
The amounts here are approximate, and meant for about 2 small to medium fillets, but feel free to experiment!
Lemon Vermouth Fish Fillet
A pat of butter, melted in the microwave in a cup or bowl large enough to add the other ingredients.
(Be careful, it melts very fast, in a few seconds)
Into the melted butter, stir:
1 Teaspoon of Dijon Mustard
1/4 Cup of Lemon Juice or Lime Juice
1/4 Cup of Dry Vermouth (the white kind, that's used in martini's)
Stir in dry or fresh herbs. Use whatever you like. Parsley, Basil, Thyme, Dill are all good.
Black Pepper (add salt if you wish, but I don't think it needs it.)
2 small to medium fish fillets
Combine the ingredients, and pour the liquid over the fish fillets, in a baking dish deep enough to hold the liquid.
Bake it in the oven at 375 degrees for about 20-30 minutes.
Timing will vary a bit, depending on the size of your fillets and if they are fresh or frozen. Typical wisdom is to always thaw a frozen fillet, but, if the fillets are not very large, I often don't thaw them first. If you have an enormous fillet, you will want to assure the center is cooked before the edges get crispy. So in that case, thawing first is a good idea. A fresh fillet will cook faster than a frozen one. Check that fish is baked through in the middle, and flakes with a fork. Leave it in longer if it needs it, checking every 5 minutes. This liquid helps keep the fish moist and adds lots of great flavor. When it easily flakes with a fork, it's ready.