Put egg yolk, mustard and vinegar in the blender.
Add a drizzle of olive oil to obtain a creamy texture.
Taste and season with salt and pepper.
If the mayonnaise is too thinck, add a spoonful of water.
Mix 3 spoonfuls of mayonnaise with 3 spoonful of ketchup. Leave in a cool place.
Preheat the barbecue.
Remove the parsely leaves from the stem and chop finely.
Crush the pepper in a mortar.
Clean the fish. Fill the fish with cherry tomatoes and parsley.
Season with the Salt & Herbs Mixture for Fish and a little ground Kampot pepper.
Cut slashes in the fish.
Cut the lettuce hearts in two.
Brush the fish with a little Huile de Tous les Jours oil and start cooking.
Turn the fish over regularly, fry for about 10 minutes.
Add a spoonful of Huile de Tous les Jours oil and sprinkle the lettuce hearts lightly with the Salt & Herbs Mixture.
Grill the lettuce hearts for 1-2 minutes.
Place the mackerel on a dish or a plate with the grilled lettuce hearts as a side-dish with the ketchup and mayonnaise.
Add about 1 spoonful of olive oil on the grilled fish and season with the Salt & Herbs Mixture and pepper.