First thing add salt. Second, 1 Tbs does not make it that red. Third, add more seasoning in general. Mushrooms are sponages and will soak up all the flavor, but if you don't season enough they're bland. Lastly a helpful tip, add herbs and seasoning, not just salt, to your pasta water. It helps the pasta hold flavor so that even if you get a bite without anything else it will still taste good.
