Coat a 9 x 13 baking dish with cooking spray. Mix together the turkey and Northern Italian seasoning until well blended.

Cook the sausage mixture in a large nonstick skillet over medium heat until lightly browned, 3 to 4 minutes. Transfer to a plate lined with paper towels to drain.

Add onions and bell pepper to pan and cook, stirring often, until softened, 3 to 4 minutes.

Whisk eggs, milk, salt and pepper in a large bowl until blended. Spread bread in the prepared baking dish. Scatter the sausage and the onion mixture evenly over the bread. Brush with mustard. Sprinkle with cheese. Pour in the egg mixture.

Cover with plastic wrap and refrigerate for at least 2 hours or overnight.

Preheat oven to 350 degrees. Bake the strata, uncovered, until puffed, lightly browned and set in the center, 55 to 65 minutes. Let cool for about 5 minutes before serving hot.

Cut and serve strata with slices of fresh avocado.

Makes 12 servings.