In a medium bowl, whisk the mustard with the salt, and balsamic until blended thoroughly.
Slowly drizzle in the olive oil whisking quickly and continuously. The marinade should become thick and emulsified.
In a seal-able container or large zip lock bag, place your meat (pork, steak or even tofu) and thoroughly coat with the marinade.
Refrigerate and marinate for 4-6 hours, turning the meat at least once during the process.
Bake/Broil/Grill your choice of meat or tofu and serve.