Preheat your oven to 425°F (220°C).
In a small bowl, mix lemon juice, olive oil, mixed herbs, salt, and pepper. Reserve a small portion of this mixture for finishing.
Place the chicken breast between plastic wrap and gently pound to an even thickness for uniform cooking. Rub the majority of the lemon herb mixture over the chicken.
Arrange the chicken on a baking sheet lined with parchment paper.
Wash and trim asparagus; place them on another baking sheet and toss with a light drizzle of olive oil, salt, and pepper.
Peel and cube the sweet potato. Toss with a little olive oil, salt, and pepper, and spread out on a baking sheet.
Place the chicken, asparagus, and sweet potato in the oven. Roast the chicken for about 20-25 minutes until the internal temperature reaches 165°F (74°C) and the skin turns crispy. Roast asparagus for 12-15 minutes until tender and slightly charred, and sweet potato cubes for about 25 minutes until soft and caramelized.
Once cooked, drizzle the reserved lemon herb mixture over the chicken for an extra burst of flavor.
Plate the chicken with a side of roasted asparagus and sweet potato cubes. Serve warm and enjoy!