Morning girls.,
I make up a small garlic and herb dressing, which is one clove garlic mashed with some favourite herbs, no salt and I use a touch of balsalmic vinegar (coz we can't have olive oil) and then some mild vinegar (not the full malt) and a touch of water blitz it (I use my hand held smoothie mixer).
I would keep tasting it just to be sure it is what you like, then I use about 5ml on my salad leaves.
I suppose you could use mustard if it was part of a dressing just look at the lable and see the carb and sugar analysis.
I wouldn't hurt to use a wholegrain mustard, would it???