1

Bring 4 quarts of water to boil in a large pot.

2

Make sauce: Melt butter in 12-inch skillet over medium-high heat. Add shallot and ¼ teaspoon salt and cook until softened, about 2 minutes. Stir in garlic and cook until fragrant, about 30 seconds. Stir in wine and cook until nearly evaporated, about 2 minutes. Stir in half-and half, peas, tarragon, and dissolved cornstarch mixture and simmer until slightly thickened, about 2 minutes. Remove skillet from heat, cover, and set aside.

3

Add asparagus and 1 Tablespoon salt to boiling water and cook, stirring often, until asparagus is tender but still crisp at center, about 2 minutes. Using slotted spoon, transfer asparagus to large paper-towel-lined plate and set aside.

4

Return water to a boil, stir in tortellini, and cook until tender. Reserve ½ cup of cooking water, then drain tortellini and return tortellini to pot.

5

Stir sauce and asparagus into tortellini. Season to taste with salt and pepper, adding reserved pasta cooking water as needed to loosen sauce. Serve immediately with freshly grated Parmesan and lemon wedges.