In a gallon-sized resealable bag, add chicken, garlic, lemon juice, onion, olive oil, red wine vinegar, oregano, allspice, and lemon pepper.
Mix well so that all the chicken is covered in marinade.
Let marinate in fridge for at least 2-3 hours (6-8 is ideal for best flavor).
When chicken is finished marinating, pour 1 cup of chicken broth into the bottom of the Instant Pot.
Dump the entire contents of the bag (chicken and marinade) into the Instant Pot.
Place lid on pot and press MANUAL (or PRESSURE COOK) and set timer for 10 minutes.
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 5-10 minutes and then a quick release of the remaining pressure. Remove the lid.
Shred cooked chicken using 2 forks.
To make the 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).
Serve on pita bread topped with cooked chicken, cucumbers, lettuce, tomato, and homemade tzatziki sauce.
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 chicken, garlic, lemon juice, onion, olive oil, red wine vinegar, oregano, allspice, and lemon pepper into a gallon-sized freezer bag. 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 cup of chicken broth in with the frozen food. Place the lid on top, move the valve to SEALING, and press the MANUAL button. Set timer for 25 minutes. Do a 5 minute NATURAL RELEASE when the timer is done. Follow the rest of the instructions as written.