Mix together the water, milk, yeast and sugar. Keep aside until it becomes frothy.

In the meantime, beat one of the eggs.

In the bowl of an electric mixer fitted with the paddle attachment, put flour, salt and butter and mix for 2 minutes.

Now add the yeast mixture and the beaten egg and knead until you get an elastic and smooth dough. It will take about 10 minutes. The dough will be a bit sticky, but the more flour you add, the tougher the buns will get.

Shape the dough into a ball, spray it with some oil and return it to the mixer bowl.

Cover the bowl with cling wrap and let the dough rise until it doubles in volume (at least one hour).

Divide the dough into equal parts and gently roll them into 5 cm – 2 inch balls. Put them on a tray lined with baking paper. Remember to keep them 5 to 7 cm (2 to 3 inches) apart as they will rise some more. Cover them loosely with some cling wrap lightly coated in oil and let the buns rise in a warm place for at least one hour. Beat the remaining egg with one tablespoon of water and use it to brush the top of buns.

Bake the buns in a preheated oven at 200°C – 400°F (with the rack in the center of the oven) for about 15 minutes, or until the tops are golden brown. Turn the tray around halfway through baking to ensure they cook evenly.

When ready, transfer them to a wire rack to cool completely.

Put 2/3 of the salmon in a mixer with the chopped red onion. Blend into a rough/chunky paste.

Cut the remaining 1/3 of salmon in small cubes.

Put everything in a big bowl. Mix it with the remaining ingredients very well using your hands.

To shape the patties, I used a 7.5 cm – 3 inch round cookie cutter. Make the patties about 2 cm – ¾ inch thick, press them well and keep them aside.

Cut open the buns and lightly toast them. Keep them aside.

Sauté the salmon patties in a pan with oil and cook them until done (2 or 3 minutes per side should suffice). Remove the patties from the pan, sprinkle with a little lemon juice, cover them loosely with some aluminium foil to keep them warm.

To assemble your sliders, spread a little aioli on the buns, then start your layers with some mixed salad, the salmon pattie topped with aioli, the slice of tomato and the sliced red onion.

Top with the other half of the bun and serve immediately with some Patatas Alioli (click here for the recipe).