To cook meat, place meat in a pot of water on high heat, let it boil, and remove any floating scum and fat. Let it simmer for 10-15 minutes. Save some of the broth.
Remove meat from the pot, and wash it. Set aside.
In a skillet heat vegetable oil, and saute the beans lightly for 4-5 minutes.
In your slow cooker place the meat, one whole onion, the sauteed beans, salt, pepper, bay leaf, and seasonings.
Cover with a lid and cook on high for 4-4.5 hours. (or on low for 8 hours).
When the beans and the meat are almost done. In a skillet heat vegetable oil and saute the diced onion for 2 minutes, then add the garlic and cook for 1 minute.
Add the flour, tomato paste, and broth (from the meat), stir well and let it come to a boil then remove from heat. (You can add a bit of vinegar or sugar for taste)
Add the mixture to the crockpot, and let it cook for 20 more minutes.
Serve warm with rice on the side.