10 ounce filets off whole rainbow or brook trout; skin on, scaled.
1 tbsp olive oil
1 tbsp unsalted butter
½ lemon, segmented, diced 1/8″ (brunoise)
1 tbsp fresh lemon juice
½ tbsp capers
1 ¼ tbsp minced parsley
Grenobloise is a classic French sauce, composed of capers, brown butter or “beurre noisette” and lemon. This recipe is for a classic dish – La Truite Grenobloise, or trout with sauce Grenobloise. With the exception of salmon, whose skin is generally quite high in fats and highly-flavored oils, I prefer to cook fish filets, generally, with the skin on. The skin of fish like trout, walleye and other species, if properly cooked, will remain crispy while the flesh of the fish is soft and delicate.
To get crispy skin, two things are important. One is to remove all excess water, and the other is to leave your fish filet cooking on the skin side until the skin is set and well caramelized (cooking tip: “caramelization” is the result of complexation between sugars and proteins – something called the maillard reaction; any food which browns has, in fact, caramelized).
First, with the back or dull side of your knife, gently scrape the skin in one direction to remove excess water. Do not bear down too heavily or you will damage the flesh of the fish, which is delicate. Between each strok of the knife, dry your knife on a towel and repeat a few times so that all excess water is removed from the skin.
Next, season each fillet on both sides with Salt and pepper, and allow to rest for 15 minutes. With thicker filets, you can go a little longer, with thinner filets, a little less time. You want the seasoning to seep into the flesh and not simply sit on the skin and surface. Go easy on the salt, however – the acid in the sauce which follows will accent the salt, giving a perception of saltiness to begin with.
Heat the olive oil in a large saute pan over medium heat until just below smoking. Place each fillet skin side down in the oil and cook until golden brown. Do not move or lift the filet until the skin is set, lightly, golden brown and crisped, or you risk separating the skin from the filet. Turn the fillets over and reduce heat to medium and continue cooking for just a minute or two, until cooked (I prefer medium rare fish). Remove fillets to a plate.
Turn flame to low. Remove pan and allow pan cool for a few seconds. Add butter to pan and return to low heat to cook until butter is browned – not black. You can tell if the butter is at the brown, hazelnut or “noisette” stage when it gives off a pleasant, nutty aroma. If it smells of raw flour, it is not yet at the noisette stage; if it smells burnt, toss it – you’ve got Beurre noire, or black butter. Remove pan from heat and add lemon segments and juice.
Return to low heat, stir in capers and parsley. Plate fish on mound of potatoes and spoon sauce on and around fish.