Can I sub my own sauce instead of the canned tomatoes?

Yes, of course! I'd add a carrot, chopped, which I'd microwave for a minute with a couple tablespoons of water, to soften. I'd also add 1 cup of beef stock or water, which are necessary to hydrate the noodles, and some chopped fresh oregano and parsley - at least a few tablespoons of each. I hope this helps! ;o)