Hull and slice the strawberries into 1/2-inch pieces, then cut the rhubarb into 1/2-inch slices. Add both fruits to your Instant Pot along with the sugar and lemon juice, stirring well to combine. Let this mixture sit at room temperature for 30 minutes—this allows the fruit to release its juices and the sugar to begin dissolving, which helps develop better flavor and texture in your final jam.

Seal the Instant Pot lid and set it to high pressure for 1 minute. After cooking completes, allow the pressure to release naturally for 10-15 minutes before carefully opening the lid. The high pressure breaks down the fruit quickly while the natural pressure release prevents the jam from splattering.

Using a potato masher or the back of a spoon, break down the cooked fruit to your desired consistency—I prefer a chunky texture, but you can mash it more if you like smoother jam. Switch the Instant Pot to sauté mode and bring the mixture to a rolling boil, stirring frequently. Continue cooking for 3-4 minutes until the jam reaches your desired thickness; it will continue to thicken slightly as it cools, so don't overcook it.

Turn off the heat and stir in the vanilla and salt, mixing until fully incorporated. Immediately pour the hot jam into sterilized jars, leaving about 1/4 inch of headspace. Let the jars cool to room temperature before sealing—the jam will thicken further as it cools.