Heat oven to 180C/160C fan/gas 4 and line a baking tray with baking parchment. Put the peanut butter, garlic, spices and egg in a small bowl and whisk with a fork until blended. Add the chicken, one piece at a time, turning them in the mixture until coated, then place on the baking tray. Any mix left over in the bowl can be put on top of the chicken. Bake for 20 mins until the coating is firm and the chicken is tender.
Mix the vinegar and oil in a bowl then add the salad leaves, cucumber, carrot, shallot and coriander, if using. Mix and serve with the chicken.