Pour beef broth into the bottom of the Instant Pot.
Place beef roast in the Instant Pot. Top with sliced onions.
In a small bowl, mix together olive oil, garlic, oregano, lemon juice, salt, and pepper.
Pour olive oil mixture over the roast.
Place lid on pot and press MANUAL (or PRESSURE COOK) and set timer for 60 minutes (you want to cook beef roasts at a high pressure for 20 minutes per pound).
Allow 10-15 minutes to come to pressure before it starts the countdown cook timer.
Once it is finished cooking, do a natural release of the pressure for at least 10 minutes (20 minutes is ideal). Remove the lid.
Slice or shred the beef and serve on pitas with cucumbers, tomatoes, and homemade tzatziki sauce.
To Make Tzatziki Sauce:
Shred or grate the cucumber and blot with a paper towel to get rid of as much moisture as possible.
Mix together the yogurt, shredded cucumbers, garlic, vinegar and lemon juice. Add dill and salt and pepper to taste.
Keep in the fridge until serving (it's best if you let the flavors come together for about 30 minutes before serving).
Notes
Homemade Tzatziki is really easy to make, but store bought tzatziki is great as well.
You can also use ranch or cucumber ranch dressing in place of the tzatziki.
Serve this with hummus, pita chips, and fresh vegetables for dipping in the hummus.
How to turn this into a freezer meal:
Place roast, beef broth, and onion, into a gallon-sized freezer bag. In a small bowl, mix together olive oil, garlic, oregano, lemon juice, salt, and pepper. Pour olive oil mixture over the roast. Place freezer bag into freezer and it will last up to 90 days.
When ready to use, dump ingredients from bag into Instant Pot and add 1/2 cup of beef broth or water in with the frozen food. Place the lid on top, move the valve to SEALING, and press the MANUAL button. Set timer for 90 minutes (or 30 minutes per pound of your roast). Do a NATURAL RELEASE when the timer is done – I even like to let it sit in the Instant Pot for a few hours so that it falls apart so easily. Follow the rest of the instructions as written.