Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Slice the chicken breast into 1-inch pieces and halve the baby potatoes to ensure they cook at the same rate.
Place the chicken, potatoes, broccoli florets, and sliced bell peppers onto the prepared sheet pan in a single layer.
In a small bowl, whisk together the olive oil, minced garlic, dried oregano, sea salt, and black pepper.
Drizzle the herb oil mixture over the chicken and vegetables, tossing thoroughly with your hands or tongs to coat every piece.
Arrange the lemon slices across the top of the mixture to infuse the dish with bright acidity during roasting.
Roast for 20 to 25 minutes, or until the chicken is cooked through and the potatoes are fork-tender and golden.