Season the steaks with salt and let them stand at room temperature for 10 minutes.
In a bowl, combine the dry mustard, brown sugar and warm water and stir until the sugar is dissolved. Stir in the remaining ingredients.
Spread the paste on both sides of the steaks and refrigerate for 2 hours.
Bring the steaks to room temperature. Light a grill. Grill the steaks over moderately high heat for about 3 minutes per side, until they are nicely charred outside and medium-rare within. Let the steaks rest for 5 minutes before serving.