Meanwhile, start making your couscous. Bring 3 cups of chicken broth to a boil, add 2 cups of couscous, reduce heat to low, and cover. Simmer covered for 10 minutes. Uncover and fluff.
Press cancel on Instant Pot and add yogurt chicken mix into the inner pot. Close and secure the lid, and turn the valve to sealed. Set to cook for 5 minutes at high pressure.
Once time is up, open the valve all the way to release the pressure, with a quick release. Once all the steam has released and the pin has dropped, remove the lid.Serve chicken in a plate or bowl with couscous. Optional - sprinkle chopped tomato and feta on top, with Tzatziki and cut cucumbers alongside.
If you have time and want even more flavorful chicken, marinate chicken the night before and refrigerate covered overnight (for no more than 24 hours).
When your chicken is done cooking, you can open the valve carefully (steam is hot!) with either a natural release or a quick release. Same result, but natural release is slower. Don't be alarmed that quick release will be very loud.