Sear the beef on each side until browned over medium hight heat. Because of the fat content oil is not necessarily needed, but add it if the beef is lean or appears to be sticking.

Add the onions and garlic, and saute for about 5 minutes until translucent. Add enough water to cover the beef. Stir in the remaining ingredients: peppers, cumin, salt and pepper. Bring up to a boil over high heat, reduce to low and simmer for at least 2 hours. Stir and try to break it apart with a fork. Continue to simmer about 30-45 more minutes until it is tender when you tear it apart.

Alternatively, use a pressure cooker:
Follow the same directions as above, except simmer under pressure for about 30 minutes. Check and simmer under pressure for another 10 minutes. Repeat until the meat is to your desired tenderness.

Another method is the crockpot:
Combine all of the ingredients in a crock pot. Cover with water and heat on high for 4-6 hours or low for 6-8.

After the meat has cooked through,
Pull out and set the meat aside to cool. Bring the poaching liquid up to a simmer for about 20-30 minutes until it is reduced in half.

Shred the meat apart as soon as it is easy enough to handle. Stir back into the sauce and serve with a slotted spoon.