• 2 cups tomatoes, crushed by hand in addition to their juices (for example, a 28-ounce can of San Marzano whole peeled tomatoes)
• 5 tablespoons butter
• 1 onion, peeled and cut in half
• Salt
  
  

The traditional recipe: Combine the tomatoes, their juices, the butter and the onion halves in a saucepan. Add a pinch or two of salt. Place over medium heat and bring to a simmer. Cook, uncovered, for about 45 minutes. Stir occasionally, mashing any large pieces of tomato with a spoon. Add salt as needed. Remove and discard the onion.

INSTANT POT VERSION: Melt butter on saute function. I add a couple of minced garlic cloves and a whole sprig of basil. Add onion, tomatoes and salt.  Set to Manual for 20 minutes.  Do a quick release and then remove the basil stem (ok to leave any leaves that have fallen off). Do not remove the onion.  Use an immersion blender to make a smooth sauce. Simmer on Saute function if you want a thicker sauce.