My Dad's dressing recipe
Make a paste with a mortar and pestle of a small clove of garlic, pepper, maldon salt, sugar and keens mustard (I'm afraid I'm no good with the quantities I just use what seems right at the time).
Put it in your dressing jar/jug/bottle.
Add vinegar (whatever type takes your fancy. I like a malt with a dash of balsamic).
Add extra virgin olive oil.

My sister stirs hers while she ads the oil and it emulsifies. I'm too lazy - I just give the bottle a shake moments before I dress my salad.
My BIL sometimes uses lemon juice as well and seeded mustard instead of the keens powder.