Tongue is not something you'll typically find on many restaurant menus, not to mention dinner tables. Although beef tongue is very affordable, cooking it is the real trick. Cooking beef tongue Mexican style takes about four hours, but this tasty Mexican dish is worth the time. Many people who've tried this recipe have mistaken it for slow cooked roast, and were simply amazed to discover the true ingredients.
Scrub the tongue thoroughly with water. Place it in a pot, add water to cover the tongue and add the quartered onion. Bring it to a boil over high heat, then lower the heat to medium and boil for approximately three hours or until the tongue is no longer pink.
Remove the tongue from the pot and allow it to cool until you can handle it without burning yourself. Slit the area on the taste bud side of the tongue with a sharp knife. Peel off both sides of the beef tongue. If you find any small bones, gristle and blood vessels, discard. Once skinned and cleaned, slice the tongue in 1/2-inch slices, diagonally against the grain.
Heat the oil in a deep skillet over medium heat, add the onion and stir until it becomes translucent. Add the garlic and stir for one to two minutes. Add the chopped tomatoes, long green chiles, oregano and thyme. Reduce the heat to medium low and allow the mixture to simmer for approximately 15 minutes.
Add the tomato paste and mix thoroughly until it incorporates, and then the chopped capers, salt and pepper. Stir well. Add the sliced tongue and cover it with the sauce. Lower the heat to a simmer, and cook for 30 minutes. Remove from heat and serve hot.