Before starting, wash and dry all produce. Add 10 cups water and 2 tsp salt to a large pot (use the same for 4 ppl). Cover and bring to a boil over high heat. While the water boils, halve the tomatoes. Thinly slice the mushrooms. Zest, then juice half the lemon (whole lemon for 4 ppl). Cut any remaining lemon into wedges. Thinly slice the chives.

Heat a large non-stick pan over medium heat. When hot, add 1 tbsp oil (dbl for 4 ppl), then the mushrooms. Cook, stirring occasionally, until softened, 5-6 min. Season with salt and pepper. Transfer the mushrooms to a plate and set aside.

Add rigatoni to the pot of boiling water. Cook uncovered, stirring occasionally, until tender, 10-12 min. While the rigatoni cooks, heat the same large non-stick pan over medium-high. When hot, add 1/2 tbsp oil (dbl for 4 ppl), then beef and Italian Seasoning. Cook, breaking up beef into smaller pieces, until no pink remains, 4-5 min.\*\* Season with salt and pepper.

Remove pan from the heat and add sour cream, broth concentrate, mushrooms, lemon juice, 1/2 tsp lemon zest (dbl for 4 ppl), tomatoes and half the chives. Return the pan to heat over medium-low. Cook, stirring often, until the sauce thickens slightly, 1-2 min.

When rigatoni is tender, reserve 1/4 cup pasta water (dbl for 4 ppl), then drain and return to the same pot. Add 2 tbsp butter (dbl for 4 ppl) and the reserved pasta water, then toss to coat.

Divide the rigatoni between bowls. Top with the sauce. Sprinkle Parmesan and remaining chives over top. Squeeze over a lemon wedge, if desired.