Add <quantity>25<unit>g</unit></quantity> of egg, <quantity>1</quantity> egg yolk, and <quantity>1½<unit>tsp</unit></quantity> of mustard to a tall container

Add <quantity>1½<unit>tsp</unit></quantity> of red wine vinegar

Add <quantity>400<unit>ml</unit></quantity> of grapeseed oil

Mix with an immersion blender on high speed until it gets thick and creamy

Season with black pepper and salt to taste

Add the juice of <quantity>¼</quantity> lemon>. Use the immersion blender to combine. The mayonnaise is ready

Enjoy using it in salads or sandwiches!