1 cup sunflower or avocado oil (or another mild tasting oil)
1 tsp apple cider vinegar
1/2 tsp salt
1.5 tsp mustard (you can use regular or dijon)
If you want an eggless/vegan option you can substitute 1/4 cup of aquafaba (A.K.A. Liquid from a can of garbanzo beans).
Add all ingredients to a wide mouth jar. Place the immersion blender over the egg and blend for about a minute until everything is incorporated and looks like mayonnaise. The nice thing about using a jar is you can just put a lid on and put it in the fridge! It keeps for about 2 weeks. We like to add ranch seasoning to make a veggie dip or both ranch and sriracha to make a southwest ranch for tacos or southwest salad.