Place chicken breasts, oregano, salt, pepper, red pepper flakes, garlic, chicken stock, lemon juice and zest in a 6 or 8 quart Instant Pot. Mix together to combine and make sure that the chicken is not stacked on top of each other.: When you first open the Instant Pot your nose will be greeted by a citrus and garlic perfume that promises flavor, so take a moment to enjoy that. The reason you spread the chicken out is to ensure even pressure contact so every piece cooks uniformly, which affects juiciness. As you stir gently, notice the broth collecting around the chicken , a pale lemon color, and listen for the faint clink of pieces settling into the pot. A common mistake here is crowding the pot, which can cause uneven cooking, so rearrange the pieces if they overlap. If you detect any dry spots, spoon a little of the chicken stock around them so nothing sits above the liquid line.
Cook on manual high pressure for 8 minutes and once done use the quick release function. Remove chicken, cover to keep warm and set aside.: You will hear the Instant Pot hiss as it builds pressure, and after release the lid lift reveals a steamy citrus steam that smells intensely lemony. Removing the chicken promptly helps preserve texture, and covering it keeps juices locked in. The why here is simple, pressure cooks the proteins quickly, sealing moisture inside the fibers so the meat stays tender. A frequent error is letting the meat sit unprotected, which allows it to cool and tighten; keep it covered or wrapped in foil while you finish the rest.
Take 2 tablespoons of brine from the artichokes and place it in the pot. Drain the remainder of the brine and add artichokes and asparagus to the pot. Cook on manual LOW pressure for 0 minutes. Use the quick release function when done.: The little splash of artichoke brine adds concentrated savory tang, and when you add the artichoke quarters and the trimmed asparagus you will notice bright green stalks contrasting with pale artichoke flesh, which looks inviting. Cooking the vegetables briefly under steam preserves firmness while infusing the lemon broth into them. The Instant Pot's upward pressure heat is perfect for delicate vegetables because it prevents them from overcooking into mush. A common slip is overcooking very thin asparagus, so if your stalks are slender consider the note about sauteing briefly instead; you want crisp tender, not limp.
Slice the chicken and divide on four plates along with artichokes and asparagus. (see note about warming up chicken): When slicing the chicken , use a sharp knife and cut against the grain so each bite feels tender in the mouth. The slices should gleam slightly with the lemon broth, and as you arrange the artichoke quarters and asparagus around the meat think about balance of color and texture. A common mistake is slicing too early when the meat is cold, which can result in a dry mouthfeel, so if it has cooled, nestle the slices back into a bit of the hot liquid to warm through briefly before plating.
If desired you can thicken up the sauce at this point: Press the saute function. Add 1 teaspoon of arrowroot to a small bowl and scoop out some of the lemon liquid and whisk it with the arrowroot to create a slurry. Return it to the pot and let cook until it has thickened to your desired consistency. Drizzle over the chicken, asparagus and artichokes and serve with wedges of lemon.: As you press the saute button you'll hear the pot's heat increase and the broth begin to shimmer, releasing a concentrated aroma of lemon and garlic that makes the kitchen smell irresistible. Whisking the arrowroot into a bit of the warm lemon liquid creates a silky slurry that prevents lumps, and when you pour it back the sauce will slowly bloom into a glossy coating, clinging to the chicken and vegetables. The why is texture, a thicker sauce feels more luxurious and helps the flavors adhere to each bite, while a lighter broth lets the ingredients stand on their own. Avoid adding arrowroot directly to hot liquid without creating a slurry first, because it can clump and ruin the sheen; always mix thoroughly before incorporating. Taste and adjust quickly, because the sauce will thicken fast and you want to stop when it's silk rather than gluey.