Combine lemon juice, egg yolk, and a pinch of salt in the bottom of a jar that barely fits the head of an immersion blender. Melt butter for a minute in a microwave oven in a 1 cup measure with a pouring spout. The butter has to be hot not warm. This is the final step,do not microwave butter until all other components of recipe are ready, your backup water is boiling and you are prepared to serve.

Place head of immersion blender into the bottom of a jar and turn it on. With the blender constantly running, slowly pour hot butter into cup. While blending, move the immersion blender up and down, slowly, so to combine everything together, and to thicken. Continue pouring until all butter is added. This should only take about 30 seconds and the butter should emulsify with the egg yolk and lemon juice. Sauce should be thick and creamy.

If it is thin and runny, add 1 to 2 Tbs hot of boing water 1 Tbs at a time at a time while running blender until sauce is thickened. Season to taste with salt. Serve immediately, or cover with plastic and transfer mixing jar to a small pot of warm water and keep in a warm place for up to 15 minutes before serving. Hollandaise will solidify otherwise and cannot be reheated.

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