Guisado de Res (Beef Stew)

2½    pounds boneless beef chuck roast, fat and gristle removed
½     cup all purpose flour
        Salt and freshly ground pepper to taste
        shortening
       Beef stock or water or a combination
1     large onion, chopped
2     cloves garlic, minced
1     cup celery, chopped
2     cups carrots, chopped
3     serrano chilies, seeded and chopped fine
2     cups potatoes (about two large russets), peeled and cubed
1    15-ounce can of peeled, chopped tomatoes
½    cup chopped cilantro leaves
1     teaspoons ground cumin (optional)
       Extra fresh cilantro for garnish (optional)
Cut chuck roast into small bite sized pieces. Place flour in plastic bag with salt and freshly ground pepper. Shake until meat is coated completely by flour mixture. Heat shortening in Dutch oven and brown the meat, taking care to shake excess flour off the pieces before putting them into the pot. Pour stock and/or water into pot until meat is covered, making sure a half-inch or so liquid is over the beef so that it does not stick to the bottom of the pot. Simmer for about 2 hours, stirring now and then to prevent sticking. Then add onion, garlic, celery, carrots, chopped chilies, cubed potatoes, tomatoes, cilantro, and cumin, with a bit more stock or water to keep ingredients from sticking to bottom. (Dish should be of a stew-like consistency, not like a soup.) Simmer another 1/2 to 1 hour or until meat is very tender and all vegetables are well cooked. Serve with flour tortillas warmed on a griddle. (Microwaving flour tortillas makes them rubbery!)