Wash and dry all produce. Adjust racks to middle and upper position and preheat oven to 400 degrees. Bring a large pot of salted water to a boil. Trim and thinly slice mushrooms. Halve, peel, and finely dice onion. Pick tarragon leaves from stems and roughly chop; discard stems. Cut lemon into wedges. Halve, peel, and quarter shallots, then place on a large piece of aluminum foil and toss with salt, pepper, 1 TBSP vinegar (we sent more), and a drizzle of olive oil.

Wrap and seal foil around shallots to create a packet. Place on a baking sheet and roast in oven on upper rack until softened, about 25 minutes. Meanwhile, stir together 3 cups water and 2 stock concentrates in a medium bowl. Microwave on high for 1 minute. (TIP: Alternatively, bring mixture to a boil in a small pot.) Heat a drizzle of olive oil in a large pan over medium-high heat. Add half the onion and all of the rice. Cook, stirring, until translucent, 1-2 minutes.

Stir stock into pan. Bring to a boil, then lower heat and reduce to a simmer. Cover pan with a lid or foil and bake in oven on middle rack until rice is al dente, 20-25 minutes. (TIP: If your pan isn’t ovenproof, transfer contents of pan to a small baking dish before covering.) Once water boils, add gemelli to pot. Cook, stirring occasionally, until al dente, about 11 minutes. Reserve 1 cup pasta water, then drain well.

Heat a drizzle of olive oil in another large pan over medium-high heat. Remove sausage from casings. Add to pan, breaking up meat into pieces. Cook until browned and cooked through. Remove from pan and set aside. Heat 1 TBSP butter and another drizzle of olive oil in same pan. Add mushrooms and remaining onion. Cook, tossing, until tender and browned, 5-6 minutes.

Stir remaining stock concentrate, 1/4 cup pasta water, and a squeeze of lemon juice into pan. Reduce heat to low, then stir in 1 TBSP butter, sour cream, and half the tarragon. Stir in gemelli and half the sausage. Season with plenty of salt and pepper. (TIP: Add a splash of pasta water if sauce is dry.) Divide between plates and sprinkle with 1/4 cup Parmesan (1 packet) and remaining tarragon (to taste), then serve.

Stir 2 TBSP butter, shallots, and remaining sausage into rice. Using a peeler, shave zucchini lengthwise into ribbons, rotating until you get to core; discard core. Stir ribbons into rice. Season with plenty of salt and pepper. Divide between reusable plastic containers and pack with remaining Parmesan. Keep refrigerated. When ready to eat, microwave on high until hot, 2-3 minutes, then sprinkle with Parmesan.