Combine oil, onion, garlic salt, basil, marjoram, thyme and pepper in heavy plastic bag. Mix well. Add roast; coat well with marinade. Marinate in refrigerator 2 hours or overnight.

Line roasting pan with aluminum foil. Combine coarse kosher salt and water to form a thick paste. Pat 1 cup paste into a 1/2-inch thick rectangle in pan. Pat roast dry with paper towels. Insert meat thermometer. Place roast on salt layer. Pack remaining salt paste around meat to seal well.

Place roast in a 425-degree oven and roast 16 - 18 minutes per pound for rare (140 degrees), 20 - 22 minutes per pound for medium (160 degrees), or 25 - 30 minutes per pound for well done (170 degrees).

Remove roast when thermometer registers 5 degrees below desired doneness. Let roast stand 5 - 10 minutes in salt crust before carving.

If using an instant read thermometer (kind that isn't inserted before roasting) check the estimated cooking time. Take roast out of the oven 10 - 15 minutes before it should be done. You may have to poke a hole in the salt crust first before inserting thermometer. Continue roasting, if needed, and test temperature again in 5 minutes. To remove roast from salt, you may need to use a hammer. After removing crust, use a stiff pastry or vegetable brush to whisk away any remaining salt crystals.