Preheat your oven to 200°C and line a baking tray with baking paper.
To a bowl add the zest from the lemon along with the juice of half the lemon only. Then add the garlic, thyme, 1 tbs olive oil and sea salt. Mix together until combined and set aside. Butterfly both chicken breasts by placing the chicken breast flat on the chopping board. Slice horizontally into the chicken, dividing it in half, but making sure to stop about 1cm from the opposite side. Open up the chicken so it lies flat and the chicken breast is the same thickness throughout. Put both butterflied chicken breasts into the lemon marinade, make sure it’s well covered in the marinade and set aside.
Heat a large frypan over a medium heat, do not add oil to the frypan. Add the chicken breasts and cook on one side for 1 minute, until golden brown. Turn over the chicken and repeat the process, then remove from the heat.
While the chicken is cooking place the sliced red onion onto the baking tray with the asparagus. Drizzle with 1 tbs olive oil and pop the chicken breasts on top. Bake in the oven for 15 minutes until the chicken is cooked through and the vegetables are roasted.
