Preheat the grill to about 300°F and set it up for direct heat.

Remove the ribs from the packaging and pat them dry. Score the membrane on the back of the ribs, then season both sides with the kosher salt.

Combine the Greek and Cajun seasonings. Transfer the mixture to a seasoning shaker, if available, and generously season both sides of the ribs.

To make the mop sauce, combine 1/4 cup of the remaining seasoning mixture with the water, white vinegar, and ketchup.

Place the ribs directly on the grill. Mop the ribs with the sauce and turn them every 10 minutes.

Continue grilling for approximately 75 minutes, or until the ribs are tender and cooked through. Remove from the grill and serve immediately.