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 cooked 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 pasta cooks, heat the same large non-stick pan over medium-high. When hot, add 1/2 tbsp oil (dbl for 4 ppl), then the 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 the sour cream, broth concentrate, mushrooms, lemon juice, 1/4 tsp lemon zest (dbl for 4 ppl), tomatoes and half the chives. Return the pan to the stove 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 the rigatoni to same pot, off heat. Add 2 tbsp butter (dbl for 4 ppl) and the reserved pasta water, stir until butter is melted and rigatoni is coated.

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