Preheat your oven to 400°F (200°C).
Peel and dice the sweet potato into 1-inch cubes and chop the red bell pepper into bite-sized pieces.
In a large bowl, toss the sweet potato, bell pepper, and broccoli florets with 0.5 tbsp of olive oil, balsamic vinegar, and a pinch of salt and pepper.
Spread the vegetables in a single layer on a parchment-lined baking sheet and roast for 20-25 minutes until the sweet potatoes are tender.
While the vegetables roast, season the chicken breast with the remaining 0.5 tbsp of olive oil, dried oregano, garlic powder, sea salt, and black pepper.
Preheat a grill or grill pan over medium-high heat. Grill the chicken for 6-7 minutes per side, or until the internal temperature reaches 165°F.
Let the chicken rest for 5 minutes before slicing.
Serve the grilled chicken with the roasted vegetables and a fresh squeeze of lemon juice over the top.