For the tartare sauce, whisk the egg yolks, mustard and vinegar in a bowl, then slowly whisk in the sunflower oil until the mayonnaise is thick and smooth. Stir in the capers, gherkins, cucumber and cockles, saving a few cockles for garnish.
For the salad, blanch the asparagus in a pan of salted boiling water until just cooked, then refresh in cold water. Season the asparagus with a little olive oil, salt and freshly ground black pepper.
Blend the mint and olive oil in a blender until smooth, then pass through a sieve into a clean bowl.
Heat a frying pan until hot, add a little olive oil and the scallops and fry on each side for 45 seconds, then add a knob of butter and season with salt.
To serve, arrange the asparagus and scallops on serving plates, top with the cockle tartare and salad leaves. Scatter with the remaining cockles across the plate and finish with a drizzle of mint oil.