The closest I've ever made something taste like vomit is by adding [i]too much[/i] dried oregano and thyme. I find that it does have a very pungent taste and is also quite gritty.
Aside from that, check all of your ingredients and your equipment. Everything you put in a soup or a sauce contributes to its' flavour in some way, so if one item is old or otherwise not usable, it'll affect the rest of the ingredients. Is your skillet or pot dirty? Onions or oils expired?
I'd recommend following a few different recipes to learn the method and see how they turn out. After you've had a chance to learn the techniques, then you can start improvising and adding a bit of your creativity to the dish. Fact is, if everything is in good condition and of good quality, and if you're applying the proper method and techniques, it will end up being good.