Peel and finely chop the garlic. Clean the chilli, cut lengthwise, remove seeds, wash and chop finely. Mix vinegar, salt, pepper and 1 tsp. sugar. Fold in 2 tablespoons of oil. Stir in garlic and chilli.
Clean and wash the zucchini and slice or cut them lengthwise into very thin strips. In a large frying pan, sauté in 2 tablespoons of oil for 3-4 minutes. Mix with the vinaigrette and serve. Pluck the mackerel fillets into pieces and arrange on the courgette.