First you separate two egg yolks, put them with salt, sugar, mustard, garlic, pepper and a good dash of cucumber vinegar in a mixing bowl and beat it with a hand mixer. Then slowly add the oil until the sauce thickens.
Then you chop an onion and four gherkins very finely, the finer the better, and fold them into the sauce. Finally, add ketchup and stir it in until the sauce is fruity.
Excellent for burgers but also totally great for meat.