In a large stainless steel or cast iron pot, combine the salt, water and brisket. Cover and let sit for 7 days in the refrigerator. (Note: brisket must be completely submerged, so double the salt and water if necessary.)
After 7 days, drain the brine and add 1 gallon fresh water, bay leaves and peppercorns. Bring to a boil, reduce heat to low/medium low, and simmer for 3 to 3 1/2 hours.
During the last 45 minutes of cooking, add the onion, cabbage, carrots, turnip, cilantro, and potatoes. Continue simmering until all vegetables are tender.
