Prepare the chicken: Preheat the grill to high. Sprinkle the chicken with seasoning. Mace and oil, garlic and sprinkle with salt and pepper. Put the chicken breasts in a shallow ovenproof dish or tin. Turn the chicken over every few minutes to distribute the seasoning and to cook it from all sides.
Cook the chicken: Put the dish under the grill, cooking the chicken for 10 minutes, turning once, until well cooked and brown on both sides. Test by putting the point of a knife in the thickest part; the juices should run clear and the flesh should be white, not pink. Leave the chicken in the dish to add the topping.
Making the salad: While the chicken is in the grill, toss the lettuce, rocket, spring onions and artichoke hearts into a bowl. Mix the mint into the yoghurt and set aside.
Adding the seeds and dates: Turn the chicken over and sprinkle the seeds, on both sides of the chicken, pressing them on with a spoon, to make them stick. Grill the chicken for 10-20 seconds more to heat and make the seeds go brown. Add the dates and stir them with the seeds and juices around the chicken.
Serve: Slice the chicken breasts in long strips and top them on the salads with the dates and seeds. Spoon over all the cooking juices on the salad. Drizzle the minted yogurt dressing over the salad or put it in a small bowl on the side and serve.