How to make melt-in-your-mouth salmon meuniere

A melt-in-your-mouth salmon meuniere cooked in a fluffy butter foam.
This time, we will be pairing it with Grenoble sauce, one of the classic sauces of French cuisine.
The butter used for the meuniere is used as it is in the sauce, and it makes an excellent sauce with a sharp acidity that you will want to eat on a hot day, in a jiffy.
Please take a look at this recipe!
Ingredients for Sauce Grenoble (about 2 servings)
5 small tomatoes
5 g shallots (or onion if not available)
1 fillet anchovy
1/3 lemon
A pinch of lemon juice
5 g capers
10 ml grapeseed oil
30 g butter
A pinch of Italian parsley
For the croutons
1 slice of bread
Enough oil to cover
10 g butter