Sauce: Rub a small baking bowl with the garlic halves. Stir through sour milk and chervil in the same baking bowl, season. Refrigerate sauce with lid on until ready to serve.
Fish: Cut salmon into 4 on-the-spot pieces, season with salt. Brush top of fish with mustard. Place cornmeal in a shallow dish, place salmon pieces in order with mustard side down, pressing well to smooth. Heat clarified butter in a non-stick skillet until hot, reduce temperature. Fry salmon over medium heat on both sides for about 5 minutes each.
Tortilla Strips: Mix tortilla strips with lemon zest, season with salt. Divide into 4 portions and spread evenly on a baking sheet lined with parchment paper.
Bake: in the middle of the oven heated to 200 °C for about 5 minutes.
Serving: Divide tortilla strips evenly on plates. Arrange salmon on top. Serve with sauce.
Tip: Instead of clarified butter, you can also use butter in most cases.