Using a hand mixer, beat together the crème fraîche, orange zest and the rest of the ingredients for approx. 1 min. Cover and refrigerate for approx. 30 min.
Rinse the pearl spelt well and place in a saucepan filled with salted boiling water. Cook the spelt, covered, over a low heat for approx. 12 min. Remove the saucepan from the heat and set aside, covered, for approx. 12 min. Pour the pearl spelt into a bowl, cover and refrigerate for approx. 30 minutes.
Bring the onions and vinegar to a boil in a heavy-bottomed saucepan and steam the onions for approx. 1 min. – until they turn a lovely pink. Pour them into a bowl, cover and refrigerate for approx. 30 minutes.
Arrange the ingredients in 4 jars (of approx. 750ml) with tight lids. Start with dressing at the bottom, then oxheart cabbage, coriander, onions, pearl spelt, mango and finish with avocado and prawns. Garnish with fresh coriander and serve with bread. Or close the lid and keep the salad in the refrigerator for later.