Stromboli is a rolled pizza with all of the fillings on the inside. This is a simplified version of one that was featured in 2017 and includes an easy, no-cook sauce. Smarts: Occasionally reviewers say they have trouble getting the stromboli to cook all the way through, so be sure to apply a very thin layer of sauce (any extra is great for dipping) and don't skip the step to add slits on the top so that moisture can escape during cooking.
Make sauce - Combine tomato puree, oregano (portion for sauce), garlic powder, sugar, and black pepper. (Can be done up to 5 days ahead)
Make vinaigrette - Whisk together vinegar, oregano (portion for salad), mustard, and honey. Add olive oil while whisking.
Bell peppers / Mushrooms - Prep as directed and combine. (Can be done up to 5 days ahead)
Pre-cook vegetables - Heat a skillet with cooking oil over medium-high heat. Add bell peppers and mushrooms to heated oil. Saute until vegetables are tender, 5 to 6 minutes. Season with a pinch of salt. (Can be done up to 5 days ahead)
Dust a counter with flour. Roll out pizza dough into a rectangular shape. Spread sauce in a thin layer on the dough (adding too much sauce will prevent the center of the stromboli from cooking all the way through; you can save any extra for dipping the finished stromboli), leaving about a 1” / 2.5 cm edge on all sides. Top with mozzarella cheese and then mushrooms and bell peppers. (Check out this video for tips.)
Brush edges of dough with some of the whisked eggs. Starting with the edge closest to you, roll the dough into a log. Transfer stromboli to the sheet pan and cut slits in the top about 2” / 5 cm apart (make these slits fairly deep; they will allow moisture to escape and heat to get in so that the stromboli cooks all the way through). Brush top with remaining whisked eggs and sprinkle with parmesan cheese.
Bake for 28 to 32 minutes, until deep brown and cooked through. (Note: if your dough is thick, the stromboli may need a few extra minutes to bake all the way through.)
When stromboli is done cooking, allow to cool for about 5 minutes before cutting into slices.
Toss tomatoes and greens in vinaigrette. Season with some black pepper.