Set a large pot of water to boil and salt it.
Put 2 tablespoons oil in a large skillet over medium-high heat and add corn.
Cook, stirring occasionally, until corn begins to brown.
Add zucchini and some salt and pepper.
Cook, stirring occasionally, until zucchini begins to brown.
Add onion or shallots and garlic.
Cook, stirring occasionally, until onion softens, about 5 minutes.
Add tarragon and cook for 30 seconds, then tomatoes.
Put pasta in boiling water and cook until tender but not mushy, 10 to 15 minutes.
While pasta cooks continue to cook sauce, reducing heat when tomatoes begin to break down.
If sauce dries out (with plum tomatoes, this is likely), add some pasta cooking water, about 1/2 cup at a time.
When pasta is done, drain it, toss with sauce and remaining oil or butter, and serve immediately with grated cheese if desired.
