Throw the vegetable right in the pot with the pasta. You'll loose a bit of nutrients to the water, but maybe some of them are absorbed by the pasta, right?

While in the middle of making two kinds of applesauce, in the largest pots I own, I noticed that it was 5:30 and thought, “Shoot, I bet those kids will be expecting some dinner soon.” I grabbed the package of 3-cheese tortellini that I keep for such emergencies, and a head of cauliflower (must have a vegetable with every meal!), and threw them all together into my barely-big-enough pot.

Everything was going swimmingly until the pasta expanded and things started flowing over the rim of the pot.

We ate it anyway.

If you want to enjoy a bit of performance art right before you eat, simply use a pot that's a bit too small to boil the tortellini.