Smoked mackerel and apple mousse with melba toast

A simple mackerel pâté on toast makes a great summer canapé, starter or lunch item for the garden, particularly when it is offset with the sharpness of pickled cucumber, lemon beetroot, or in this case, tart Granny Smith apples. Whether you use fresh or smoked mackerel, the end result is light and creamy but intensely flavoured at the same time. This impressive and delicately-flavoured starter is perfect for entertaining without splashing the cash. Make-ahead, easy-to-do and very little cooking required,so great for this time of year,although I have been known to include it as part of a Christmas table.
Here I have used Granny Smith apples both within the mousse and as a garnish.
Smoked mackerel and apple mousse 
with melba toast
Serves 6

6 slices white bread
1 sheet leaf gelatine
100ml water
3 Granny Smith apples (reserve 2 for garnish)
50g butter
3 fillets smoked mackerel (150g)
150ml cream
1 tbsp horseradish sauce
2 tbsp lemon juice (more to dip apple slices )
Pinch cayenne pepper
20g fresh dill
2 egg whites
1 tbsp sunflower oil
Handful baby watercress
Salt and pepper

For Melba toast, slice the bread wafer thin.Lay on a baking tray and bake in a medium oven until the slices start to curl up and away from the tray.(about 20 minutes depending on how fresh the bread is)

Peel, core and cube one of the apples and cook until slightly softened in the butter. Set aside to cool. Soak the leaf gelatine in cold water for a few minutes to soften. Squeeze excess water from the sheet before adding it to 100ml just boiled water, and allow to cool.

Remove the skin and blitz the mackerel fillets and cooked apple together. Add the cream, horseradish sauce, 1-2 tablespoons of lemon juice (to taste), pinch of cayenne, fresh dill and cooled gelatine. Blitz until combined, taste, then season with lots of black pepper.

Whisk two egg whites to soft peaks, gently fold in to fish mixture.

Lightly oil six ramekins or moulds with an unscented oil and pour mackerel mousse into each ramekin. Fill to the top. Allow to set for four hours, or overnight, in the fridge.

Cut the apples for the garnish into wafer thin discs. Dip the slices in lemon juice and press between two sheets of clingfilm so they do not discolour.

To serve, release mackerel mousses from moulds (briefly dip each ramekin base in a bowl of boiling water) and turn out. Garnish with baby watercress. dill or fennel fronds and serve chilled with the Melba toast.