Bring a medium saucepan of water to a boil. Fill a bowl with ice water. Using a paring knife, core the tomatoes, and make a shallow X in the bottom of each one. Blanch the tomatoes in the boiling water until their skins just begin to split, about 30 seconds. Using a slotted spoon, transfer the tomatoes to the ice water to cool, then drain, and peel. Halve the tomatoes and discard the seeds. Cut the tomato flesh into 1/2-inch dice.

Bring a pot or large saucepan of salted water to a boil. In a large skillet, heat the olive oil. Add the sliced zucchini and cook over moderate heat, stirring occasionally, until almost tender, about 3 minutes. Add the diced tomatoes and cook until they begin to break down, stirring occasionally, about 2 minutes. Season with salt.

Cook the farfalle in the boiling water until al dente, adding the asparagus to the pot 1 minute before the pasta is done. Drain the pasta and asparagus well, reserving 1/2 cup of the cooking water.

Return the pasta and asparagus to the pot. Add the zucchini-tomato mixture, along with the spinach, tarragon, and the reserved pasta water and season with salt. Spoon the farfalle into bowls, sprinkle with the ricotta salata, and serve.