For the crusted pistachio chicken, rub the chicken in olive oil, roll in the chopped pistachios and season with salt and freshly ground black pepper. Drizzle with a little more olive oil, heat a griddle pan and griddle the chicken for 3-4 minutes on each side, or until completely cooked through.
For the pea mash, cook the peas in a pan of boiling salted water for 2-3 minutes. Drain and return to the pan with the butter, salt and freshly ground black pepper. Process with a hand blender until smooth, adding a little water if the mixture is too thick.
For the fennel salad, place all the salad ingredients into a large bowl and stir well.
To serve, place the pea mash onto a serving plate, top with the spiced chicken and place the salad on the side.