1. Pre-heat oven to 375 degrees. Tie short ribs together with kitchen string, then salt and pepper. Heat olive oil in a large Dutch oven over medium-high heat, and brown short ribs on each side. Remove short ribs, and add carrots, celery, and onions to pan and cook to a golden brown, 5 to 10 minutes. Add tomato paste and flour, and cook 2 to 3 minutes.
2. Return short ribs to the pot, and deglaze with port and red wine. Cook until liquid is reduced by two-thirds. Bunch rosemary, parsley thyme, and bay leaves together and tie the bundle with kitchen string. Add garlic, the tied herbs, and stock. Bring to a boil, cover, and transfer to oven for 3 hours, until meat is fork-tender.
3. Transfer short ribs to a platter. Strain sauce through a fine sieve or cheesecloth into a medium-size saucepan. Reduce sauce over medium heat until it thickens. Adjust seasoning, spoon sauce over short ribs, and serve.