Wash and dry all produce. Bring a large pot of salted water to a boil. Remove sausage from casings; discard casings. Trim, then thinly slice scallions, keeping greens and whites separate. Core and seed tomato, then dice into 1/2-inch cubes. Cut lemon into wedges.

Heat 1 TBSP oil in a large pan over medium-high heat. Add scallion whites, sausage, and Italian seasoning, breaking up meat into pieces. Cook, tossing, until sausage is browned and cooked through and scallions are softened, 3-5 minutes. Stir in tomato and cook until just softened, 1-2 minutes.

Once water boils, add ravioli to pot. Cook, stirring occasionally, until al dente and floating to the top, 4-5 minutes. Scoop out and reserve 1/2 cup ravioli cooking water, then carefully drain. TIP: Gently shake your strainer with the drained ravioli in it to dry them off as much as possible.

Reduce heat under pan with sausage mixture to low, then add a squeeze of lemon juice, a small splash of reserved ravioli cooking water, and stock concentrate. Give everything a stir, scraping up any browned bits on bottom of pan. Stir in 1 TBSP butter and sour cream. Season with salt and pepper. TIP: Add more cooking water as needed to give sauce a loose consistency.

Carefully stir ravioli into pan. Season with salt, pepper, and a squeeze or two of lemon juice (to taste).

Divide ravioli mixture between bowls, then sprinkle with scallion greens. Serve any remaining lemon on the side for squeezing over.