Cut the chicken into 2.5cm cubes. Cut courgettes into thin strips and blanch in boiling water for 30 seconds. Place lemon zest, lemon juice, mint, coriander, spring onions, crushed garlic, salt and pepper into a food processor. Chop finely to combine. Add enough olive oil to make a marinade paste and rub all over the chicken. Allow to sit in the fridge, covered, for up to an hour.
Dice the peppers and pineapple into 2.5cm cubes. Using skewers, spike each piece of meat alternatively with peppers, pineapple and courgette strips.
Grill in a hot oven for 5 minutes, turning regularly until the meat is cooked and evenly browned – cut open a piece of chicken to check it is thoroughly cooked.