2 Egg yolks,
1 Cup oil,
1-2 Tbsp. lemon juice or white wine vinegar (I use lemon juice)
1/2 teaspoon salt,
1/4 tsp. dry mustard...
Of course, add seasonings to your taste.
Now, you have to REALLY whip this recipe a lot so it would be best to do it in a food processor, mixer or with a hand-held mixer. I make mine in my mixer with the whipping attachment.
Whip the egg yolks until they start to stiffen a bit. then add the lemon juice, salt and mustard, and mix together. While leaving the mixer or processor on, slowly drizzle in the oil until the mixture emulsifies and thickens.
It takes 10 minutes and costs pennies!