Preheat the oven to 300° F. Line a large rimmed baking sheet with parchment paper and lay the salmon fillet on it. Pat dry with a paper towel. Whisk the oil, lime zest, and garlic together. Grate the jalapeño and smell for spiciness. If it is very spicy (or you are sensitive to spice) add only half the grated pepper. Otherwise, add it all to the oil mixture. Pour or spoon the mixture over the salmon fillet and salt and pepper liberally. Bake for 10 to 15 minutes, until just cooked through, but not dry. The fish should feel just firm in the center and should be just beginning to flake when you poke into it. An instant-read thermometer should read 120° F. Squeeze lime juice over the top and serve warm.