Prepare all roasting vegetables (tomatoes, mushrooms, pepper, garlic, onions) as indicated above. To simplify garlic peeling, smack the garlic clove with the flat side of the knife, the peel will just come right off.
In a large bowl combine chopped plum tomatoes, quartered mushrooms, chopped green pepper, garlic cloves, and chopped onion. Add 2 T Balsamic vinegar and 2 T olive oil and toss to combine well.
Place vegetables into a large roasting pan, sprinkle with salt and pepper, and into the oven. Roast, stirring occasionally, until the onions and garlic are golden brown and nearly all the liquid from the mushrooms and tomatoes has evaporated, about 40-50 mins, could be longer depending on the size of the pan.
Reduce oven temperature to 325°F.
Sprinkle chicken with salt and pepper and 1 T rosemary.
In a large skillet add remaining 3 T oil and heat on medium heat until oil is hot. Add one thigh at a time, making sure not to crowd them. I do them in a couple batches.
Brown both sides of the thighs until a golden brown, putting chicken into bowl as they are done.
Add wine and chicken broth to skillet and simmer until reduced by 1/2 scraping up any browned chicken bits that stuck to the bottom. Add canned tomatoes with liquid and combine thoroughly.
Remove roasting pan from oven. Nestle chicken in roasted vegetables and pour wine mixture over the top. Sprinkle remaining 1 T rosemary, marjoram and 1/2 of capers. Stir gently, incorporating any brown bits that may have stuck to the sides of the roasting pan.
Return roasting pan to oven and bake for 15 - 20 mins, or until chicken is done and juices run clear. Top with remaining capers.