- Put one egg and one extra yolk into a food processor with the juice of half the lemon and mustard powder. Mix well, then leave the motor running and slowly add the oil through the feed tube. The mixture will absorb the oil and thicken to a glossy mayonnaise. Season with salt.
- Remove to a bowl and cover the surface with plastic wrap, pushing down to exclude all air. This will prevent a skin forming.
- The mayonnaise will keep for 3-4 days in the fridge.