Mix the lemon juice, half the oil, the oregano, thyme, salt and pepper and coat the chicken. Leave 10 minutes while the oven heats.
Preheat the oven to 200°C (400°F) with a rack in the centre.
Rinse the quinoa and add it to a saucepan with 480 ml (2 cups) of water. Bring to a boil over high heat, cover, simmer on low for 15 minutes and rest covered 5 minutes.
Heat a large oven-safe skillet over medium-high heat. Snap the woody ends off the asparagus and toss the spears with the rest of the oil and a pinch of salt.
Sear the chicken for 3 minutes per side until golden.
Add the asparagus around the chicken and move the skillet to the oven. Roast for about 12 minutes, until the chicken reaches 74°C (165°F) in the thickest part and the asparagus is tender.
Rest the chicken 5 minutes, then slice and serve over the quinoa with the asparagus and parsley. Spoon any pan juices over the top.
Tips
Pound thick breasts to an even thickness so they cook evenly.
Swaps
Low-FODMAP: swap asparagus for green beans (asparagus is high-FODMAP).