What's Too Processed?

I'd say if you can't pronounce the ingredients on the label then it's too processed. For example, there is absolutely no reason for a bottle of mustard to have anything in it other than mustard, water, vinegar, and spices.

I would really love to know that too...I know the most obvious is to only buy whole foods but I'm having a really difficult time shopping because I feel like everything I pick up has something added to it! For ex, what kind of bread do you buy?

Everyone probably has their own definition... the one that works best for me is:
- if you can't pronounce or recognise the ingredients it is probably too processed.

Oh, and not toooooo many ingredients. Processed stuff has lots of "fillers" - cheap refined sugars/carbs which don't offer you any nutritional value but bulk out the product and let the company make more money!

Tofu should be fine. Check your soy sauce bottle but it shouldn't have much for in it than fermented soy beans.
Soy milk - well, that's a whole other topic, lots of people say there are problems with soy. I would keep consumption of this down if you can.
Bread - check the label, go for as few ingredients as possible, and buy one with lots of grains.
Honey and maple syryup - just make sure they are pure and have no additives
Vinegar - should be fine, usually just made from fermented grapes.

A good guide is that often the best food doesn't have claims all over the label.
If it has to tell you it is "low fat", "fat free", "sugar free" there is a good chance they've messed with it to be able to make those claims. Almost all these kinds of products will be "too processed".

if you can't pronounce the entire ingredient list its too processed. that being said things like white bread and refined sugar are not bad for you. even your best whole wheat breads are only about 40% whole wheat, that combined with the extensive milling process whole wheat bread is not that much better. however I personally do prefer them for the slightly nutty flavor. refined sugar the good stuff al least is heated and cooled repeatedly so that the pure sucrose will crystalize, the crystals are then extracted.
if you mash whole soybeans then extract the pulp, and heat it until the proteins separate the curds are tofu and the liquid left over is soy milk. soy sauce is fermented soy juice with some added salt. so none of what you've mentioned is terribly processed, just stick to the first rule and you'll be fine.