Mayonnaise
I've made this and it's fantastic.
1 egg
2T. lemon juice
1/8 tsp. dry mustard
1/2 tsp salt
dash pepper
garlic powder
onion powder
3/4 cup oil
Add all ingredients except oil to blender. Begin whirling, slowly drizzling the oil in until gone. Occasionally stop and scrape down the sides if needed. Stores well for two weeks in fridge.