Pour 1 cup water in the bottom of a 6-quart instant pot (if using an 8-quart pot, add 1 1/2 cups water). Place the trivet on top with the “feet” touching the bottom and the handles pointing up and resting on the sides of the pot.

Pat the salmon fillets dry on both sides. Arrange in a single layer on top of the trivet. Sprinkle with the salt, pepper, and herbs (if using). Lay 1 lemon slice on top of each fillet (if using).

Seal the Instant Pot. Cook on manual (high) pressure for 1 minute (for fresh fillets) or 4 minutes (for frozen). The pressure will build, then the cook time will start. Once the cook time finishes, immediately vent to release the pressure. When the pin drops, carefully open the Instant Pot lid.

Check the salmon for doneness—it should register 135 to 140 degrees F on an instant read thermometer inserted at the thickest part. If the salmon is 145 degrees F or more, use a trivet to carefully remove it from the Instant Pot and serve immediately; if it's between 135 and 140, let it sit in the pot, uncovered, for 5 minutes to come to temperature, then serve; if it’s less than 135 degrees F, recover the Instant Pot and let the salmon sit a few minutes more to continue cooking in the warm pot. Enjoy hot with a pinch of salt and pepper to taste.