Spray the instant pot with non-stick cooking spray. Place pieces of pork in the pot (cut off large pieces of fat) and pour in chicken broth and sprinkle with salt and pepper. Place on the lid and set the knob to sealing. Push the pressure cook button and set the time for 1 hour. When the time is done, let it self release for at least 15 minutes. Then turn the knob to venting. When the silver button goes down, open the pot and shred the pork in a separate bowl.

While the pork is cooking, cut the pineapple into tidbits and slice the onions. Combine the sugar and cornstarch in a small bowl. In a medium sauce pan, combine the sugar mixture, pineapple and lemon juice. Turn the heat to medium and stir until it comes to a boil and thickens. Turn off the heat.

In a 12 inch skillet, melt the butter on medium high heat. Add the onions and saute until they are golden brown. Add them to the pineapple mixture and stir until combined.

Heat the griddle to 350°F. Generously, butter one side of two pieces of bread. Place one piece of bread on the griddle, butter side down. Spread mayonnaise on the bread, add a slice of cheese, a spoonful of pork, a spoonful of the pineapple onion sauce, and then top it with the other slice of bread, spreading with mayonnaise before placing it butter side up on the sandwich. Grill both sides until golden brown. Enjoy!