Prep veggies: Slice peppers into 1" strips. Roughly chop tomatoes and onions. Slice fennel into 1/2" strips. Peel and smash garlic.
Place prepped veggies on rimmed baking sheet. Toss with olive oil, vinegar and salt.
Roast for 30 minutes.
Add roasted veggies (and any accumulated juices) to a medium heavy-bottomed stock-pot along with broth and italian seasoning. Bring to a simmer and cook for 10 minutes.
Remove soup from heat and puree with an immersion blender. Finish with salt and pepper to taste.