I like to use gallon-size storage bags. Dry the meat and onions, and try to separate them. Season the beef well with salt and pepper. Saute the onions until lightly wilted. Remove from pot and set aside.
Good browning seals the meat and provides a richer flavor.
Add all of the onions and marinade, bring to a simmer, cover and place in preheated oven. Bake for about an hour or two. Stir in the carrots and tomatoes, and bake for another hour or two. Taste and adjust seasoning. Serve over egg noodles, with bread, or over cooked potatoes.