Place the top oven rack in the center position and pre-heat the oven to 400ºF. Place a large cast iron skillet inside to warm up while the oven pre-heats.
Carefully remove the hot skillet from the oven and add the olive oil. Gently swirl the oil around the bottom of skillet until coated. Arrange the sausages, red onion, garlic cloves, and tomatoes in the skillet. Season with the Italian seasoning and a generous amount of salt and black pepper, to taste.
Place the skillet in the oven and roast for 20-25 minutes.
Remove from oven and add the white beans and red wine vinegar to the skillet and gently stir to combine. Be sure to flip the sausages so the bottom has a chance to brown evenly.
Return to the oven and cook for another 10-15 minutes or until the sausages are nicely browned.
Remove the skillet from the oven and remove the whole garlic cloves. Squeeze the roasted garlic into the skillet and top with the fresh basil. Stir to combine and serve immediately. Enjoy!