Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Peel and dice the sweet potato into 1/2-inch cubes and chop the broccoli and bell pepper into bite-sized pieces.
Slice the chicken breast into even 1-inch strips to ensure quick and even cooking on the sheet pan.
In a small bowl, whisk together the olive oil, lemon juice, rosemary, garlic powder, salt, and pepper.
Place the chicken and all the vegetables onto the prepared sheet pan and drizzle the lemon-herb marinade over the top.
Toss everything well with your hands or tongs until evenly coated, then spread it out into a single layer.
Roast for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender.
Allow the mixture to cool slightly before transferring it to a meal prep container for a delicious, dairy-free lunch.