In a skillet, heat olive oil over medium heat. Sauté the onion & garlic.
When the onions are tender and beginning to get a little golden, add in tomato paste, thyme, red pepper flakes, and the Worcestershire sauce. Stir them all together and let them cook for about a minute.
Mix in the flour.
Stir in the balsamic vinegar, red wine, and chicken broth. Allow that to cook together for a minute on low heat.
Remove it from the heat and stir in the tomatoes. Pour the rich goodness into your slow cooker.
Stir in the wine, broth, salt & pepper.
Now nestle the chicken down into the darkness.
Note: Chicken thighs can at times be rather fatty. I take a pair of kitchen shears and trim all the excess fat from the meat before cooking.
Put the lid on your slow cooker and allow the chicken to cook 6-8 hours on low. Serve this over couscous or rice, whichever you prefer.