1. For the pickled cucumbers: wash and slice the cucumbers into quarters. Place the cucumber slices into a clean jar with a lid. In a small saucepan, combine the white vinegar, water, granulated sugar, salt and black peppercorns. Heat over medium heat, stirring occasionally, until the sugar and salt have dissolved. Pour the hot liquid over the cucumber slices in the jar, making sure to cover them completely. Let the mixture cool to room temperature. Once the mixture has cooled, seal the jar tightly with the lid and refrigerate for at least 24 hours before serving. The pickled cucumber pieces will keep in the refrigerator for up to two weeks.

2. For the ceviche: in a medium sized bowl, mix together the mackerel pieces and lime juice. Season with salt and pepper to taste and stir to combine. Cover and refrigerate for 30 minutes to one hour, to allow the fish to marinate in the lime juice.

3. In a small bowl whisk the crème fraîche and wasabi paste until well combined. Set aside. Once the mackerel has finished marinating, drain off any excess lime juice and transfer the fish to a large mixing bowl. Add the sliced pickled cucumber and halved cherry tomatoes to the bowl with the mackerel. Stir to combine.

4. To serve, divide the mackerel ceviche mixture among two serving plates. Drizzle the crème fraîche and wasabi mixture over the top of each plate. Sprinkle with chopped coriander leaves and a drizzle of olive oil.