Add the beef, lard, water, salt, onion, and garlic to a large pot. The water should partially cover the meat.
Bring to a simmer and cook for 1½-2 hours, or until the beef is very tender. The water will gradually reduce during cooking. Once most of the water has evaporated, the beef will begin cooking in the rendered fat.
Carefully remove the meat and chop it into small taco-size pieces.
Return the chopped meat to the pot and cook it in the hot fat for several minutes, stirring occasionally, until browned and lightly crispy.
Heat the tortillas on a hot skillet or comal until soft and lightly charred.
Fill tortillas with the suadero and top with chopped onion, cilantro, salsa, and a squeeze of lime. Serve immediately.
