Hot sauce, mustard, light mayo, pickles, cheese are all staple condiments for me to have around if going low carb.
A big homemade burger patty with cheese, mustard, mayo and pickles wrapped in romaine is hard to beat! Sometimes I would add an egg for the royale effect and a squirt of sugar-free Heinz if I could make it work. You gotta really watch that stuff if keto, but a little makes a big pop. Also, some flax wraps out there are indecently good with taco meat.