Gut the trout by slitting open its belly from the vent or anus, just below its hind fins, all the way to the throat. Use just the tip of a sharp knife to avoid cutting open its stomach or intestines. Remove the entrails with your knife or a finger, then rinse the cavity thoroughly with cold, running water.

Pat the trout dry with clean paper towels. If you want to cook the trout whole, it's now ready to use. The head can be removed or left on.

Fillet the trout by making a vertical cut immediately behind the gills, then turning your knife horizontally and following the line of the spine all the way to the tail. Turn the trout over and repeat on the other side. Alternatively, butterfly the trout by making a cut on either side of the backbone to sever it from the ribs, without cutting through the skin. Reach under the spine with the tip of your knife and sever it from the flesh, then pull it out with your fingers.

Trim the rib bones from the filleted or butterflied trout by laying your knife flat, and gliding it under the severed end of the bones. Make a long, slow cut with your knife, keeping it pressed against the underside of the bones. The entire plate of ribs and the membrane holding them together should come away in one piece. Repeat on the other side or for any remaining fillets.

Season brook trout fillets or butterflied trout lightly with salt and pepper or other flavorings, as desired. Season whole trout inside and out.

Clean the bars of your grill carefully, and oil or spray them with high-temperature pan spray. Preheat the grill to medium-high heat. For pan-searing, place a heavy skillet over medium-high heat.

Place the fillets or butterflied trout in an oiled fish grilling basket, and place them on the grill. If you're pan-searing the trout, add 1/2 tablespoon of oil to the hot skillet and put in your first few fillets or whole trout. Leave plenty of space between the portions and don't crowd the pan.

Cook fillets or butterflied trout for 2 to 3 minutes on each side, until they're lightly browned and opaque at the thickest part of each fillet. Cook whole trout for 3 to 4 minutes per side, or until the flesh lifts easily from the backbone.

Preheat your oven to 425 degrees Fahrenheit. Arrange your fillets, butterflied trout or whole trout evenly on a parchment-lined baking sheet.

Brush or spray the trout lightly with cooking oil, or brush them with melted butter for a richer flavor. Season them with salt and pepper, lemon, fresh herbs, or other flavorings as desired. Season inside the belly cavity of whole trout, and garnish the cavity with a lemon slice or fresh herbs if you wish.

Bake fillets or butterflied trout for 7 to 10 minutes, depending on their size, until the thickest portion of the fillet is opaque when you cut into it with the tip of your knife. Whole trout require 12 to 15 minutes, depending on their thickness. They're done when the flesh lifts easily from the backbone.