Preheat the oven to 180°C/gas mark 4. Place a griddle pan over a medium heat and coat the chicken breasts with the olive oil. Place the chicken in the griddle pan and cook for 5-6 minutes on each side, until there are dark golden griddle marks. Place on a small baking tray in the oven for 8-10 minutes, until cooked through.
Place all the remaining salad ingredients in a large bowl.
Whisk the dressing ingredients together in a jug and season. Drizzle over the salad and divide between two plates, then slice the chicken breasts and place on top of the salad.