⅓ cup apple cider vinegar
1 tablespoon caster sugar
½ teaspoon sea salt
good grind pepper
1 tablespoon wholegrain mustard
1 small red onion, very finely sliced
250 grams fresh salmon
1 slim telegraph cucumber or 3 Lebanese cucumbers
1 small fennel bulb, very thinly sliced, fronds reserved
Put the vinegar, sugar, salt, pepper and mustard in a small saucepan and bring to a boil. Add the onion and simmer for 1 minute. Tip into a large bowl and chill until cold.
Slice the salmon thinly against the grain and add to the chilled marinated onions, tossing to coat the salmon in the liquid.
Shave the cucumber with a vegetable peeler into long thin slices, discarding the inner core. Add to the salmon along with the shaved fennel and half of the roughly chopped fennel fronds.
Transfer the salad to bowls and garnish with more fennel fronds and a drizzle of olive oil. Season with salt and pepper.