favourite sandwich/wrap spreads and sauces

I agree, avocados are great. I also use hummus (I'm obsessed with hummus) :P

Mustard! It's literally calorie-free. As long as it's not like honey mustard or anything. Also for pastas and soups and stuff I like to add in some Boboli pizza sauce because I'm obsessed with tomato flavor, but that might not work for sandwiches. And roasted bell peppers have a great flavor for any kind of Caprese-esque sandwich/salad (i.e. mozzerella, basil, tomato, etc.) but are pretty expensive. I don't like sundried tomatoes but if you do those are an option. And pesto, but it's made with oil so it's pretty caloric (same with avocados). It's good fat, but you need to be careful about portions. Also pickle slices are great for sandwiches and are also almost calorie-free. And if you like sour cream on tacos or whatever then you can substitute fat-free Greek yogurt for that same creamy, sour taste but with the calories coming from protein as opposed to fat. I've also heard you can mix those salad dressing powder packets (ranch or whatever) into Greek yogurt and it comes out tasting like regular salad dressing but with the same fat/protein swap.