Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel and dice the sweet potato into half-inch cubes and slice the red bell pepper into thin strips.
Place the sweet potato and bell pepper on one side of the baking sheet, tossing with 0.5 tsp of olive oil and a pinch of salt and pepper.
Season the chicken breast with the dried oregano, remaining salt, remaining pepper, and 0.5 tsp of olive oil, then place it on the other side of the tray.
Roast in the oven for 20 to 25 minutes until the chicken reaches an internal temperature of 165°F and the potatoes are tender.
While roasting, lightly steam the chopped Pak Choi for 3 minutes until the leaves are wilted but the stems remain slightly crunchy.
Slice the roasted chicken into strips and assemble your bowl by layering the cooked quinoa, roasted vegetables, steamed Pak Choi, diced red onion, and cherry tomatoes.
Squeeze fresh lemon juice over the entire bowl before serving to brighten the flavors.