This recipe makes a reasonable amount of mayonnaise, so that you don't have too much leftover. It is also easily doubled for occasions when you need more. Making it gets a lot easier with practice.
Whisk the yolk, water, lemon juice,and salt until it is frothy and light in color. Trickle the oil down the sides of the bowl while whisking, allowing time for it to be incorporated. Continue whisking and drizzling in the oil.
Once the yolk mixture begins to develop a thicker consistency like yogurt, you can increase the flow of oil, pulling back if the mixture begins to look curdled until it is smooth once again. Continue whisking until all of the oil is used up and the mayonnaise is satiny smooth.
If, for some reason, your mayonnaise does not thicken, it is fixable. Start over in a clean bowl with another elk yolk and whisk it well. Then trickle in the thin mayonnaise while whisking until your mayonnaise has thickened. If it's too thick, you can then thin it with lemon juice or water.