Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Mince the garlic clove finely.
In a small mixing bowl, whisk together 0.5 tbsp of the olive oil, the lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Place the chicken breast on the prepared baking sheet and brush the lemon-herb mixture evenly over both sides.
Roast the chicken in the oven for 10 minutes.
While the chicken is roasting, trim the woody ends off the asparagus and toss the spears with the remaining 0.25 tbsp of olive oil.
Remove the baking sheet from the oven, place the asparagus next to the chicken, and return to the oven for an additional 10 to 12 minutes.
Ensure the chicken has reached an internal temperature of 165°F and the asparagus is tender and slightly charred.
Serve the roasted chicken and asparagus over the warmed cooked brown rice, drizzling any remaining pan juices over the top.