Preheat your oven to 400°F and line a large rimmed sheet pan with parchment paper for easy cleanup.
Wash and dry the baby red potatoes, then cut them into uniform halves or quarters to ensure they cook through evenly.
Trim the woody ends off the asparagus spears and slice the red bell pepper into thin strips.
Cut the chicken breast into 1-inch bite-sized cubes and pat them dry with a paper towel.
Place the potatoes on the sheet pan, drizzle with 1 teaspoon of olive oil and half the salt, then roast for 12 minutes.
Remove the pan from the oven and add the chicken, asparagus, and red peppers to the tray.
Drizzle the remaining oil over the new additions and sprinkle the garlic powder, oregano, black pepper, and remaining salt over everything.
Toss all ingredients together on the pan to coat thoroughly, then spread them out into a single layer.
Return the pan to the oven and roast for another 15 to 18 minutes until the chicken is cooked through and the potatoes are golden.
Finish the dish by squeezing the juice of half a lemon over the hot chicken and vegetables before serving.