Bring a medium pot of salted water to a boil. Wash and dry all produce. Trim ends from zucchini; shave zucchini lengthwise into thin ribbons using a peeler, rotating as you go. Stop once you get to the seedy core; finely chop core. Dice tomato. Trim and thinly slice scallions, separating whites from greens. Zest and quarter lemon.
Once water is boiling, gently add ravioli to pot. Immediately reduce to a low simmer. Cook, stirring occasionally, until al dente and floating to the top, 4-5 minutes. Reserve 1 cup pasta cooking water, then drain. TIP: Gently shake strainer with ravioli in it to remove as much moisture as possible.
Heat a large drizzle of olive oil in a large pan over medium-high heat. Add chopped zucchini, tomato, scallion whites, and Italian seasoning; cook until veggies are just softened, 1-2 minutes. Season with salt and pepper.
Reduce heat under pan with veggies to medium; stir in stock concentrate, a squeeze of lemon juice, and ⅓ cup reserved pasta cooking water. Reduce heat to low and cook 1-2 minutes. Stir in sour cream and 2 tablespoons butter. Season with salt and pepper. TIP: If needed, stir in more reserved cooking water a splash at a time until sauce reaches a creamy consistency.
Separate zucchini ribbons with your hands, then stir into pan with sauce. Carefully stir in ravioli. Simmer until sauce is thickened, 1-2 minutes. Season with salt, pepper, and lemon zest to taste.
Divide ravioli mixture between bowls. Garnish with scallion greens and Parmesan. Serve with any remaining lemon wedges on the side.