Super easy and you could easily make this a flavored mayo.
1/4 cup liquid egg yolk (safer to use)
1/2 tsp. salt
1/2 tsp. dry mustard
2 pinches of sugar
2 tsp. lemon juice
1 tbsp. white wine vinegar
1 cup corn oil
In a food processor whisk together egg and all the dry ingredients. Combine vinegar and lemon juice in a small bowl. Add half of it to the food processor, and then half the corn oil. Add remaining vinegar/lemon juice and pulse, and then remaining oil. It will be thick just like mayo.