Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce.
In a medium pot, combine stock concentrate and 7 cups water. Bring to a simmer, then reduce heat to low.
Trim and thinly slice scallions, separating whites from greens. Peel and mince or grate garlic. Halve, core and slice bell pepper into 1/2" thick strips. Quarter lemon.

Heat a large drizzle of olive oil in a large pan over medium-high heat. Add sausage and cook, breaking up meat into pieces, until browned and cooked through, 4-6 minutes.
Turn off heat. Using a slotted spoon, transfer sausage to a paper-towel-lined plate, leaving as much oil in pan as possible.

Heat pan with reserved oil over medium heat; add scallion whites, garlic, risotto and 1/2 teaspoon Italian seasoning. Cook, stirring, until scallion whites are softened and rice is translucent, 1-2 minutes.
Add 1/2 cup stock; stir, scraping up any browned bits from bottom of pan, until liquid has mostly absorbed.

Repeat process with remaining stock--adding 1/2 cup at a time and stirring until liquid has mostly absorbed--until rice is al dente and mixture is creamy, 25-30 minutes. TIP - Depending on the size of your pan, you may need a little more or a little less liquid.

While risotto simmers, toss bell pepper on a baking sheet with a large drizzle of olive oil and 1 teaspoon Italian seasoning. Season with salt and pepper.
Roast on top rack until softened and lightly charred, 15-20 minutes.

Once risotto is done, stir in sausage, roasted bell pepper, half the Parmesan and 3 tablespoons butter. Add a squeeze of lemon juice to taste and season with salt and pepper.
Divide between bowls and sprinkle with scallion greens and remaining Parmesan. Serve with any remaining lemon wedges on the side.