4-5 pound boneless beef top loin roast from rib end. (The rib end is more tender, with less connective tissue, than sirloin end.)
Trim roast of all surface fat and silver skin (connective tissue just under the fat layer).
Use paper towels and pat trimmed roast dry, and coat with olive oil. If using cornstarch, lightly dust the top and sides of the meat. For a 4 pound roast, this will be about 1 tablespoon of cornstarch.
Mix the first eight ingredients to form a paste.
If you are using garlic cloves, you must first make a garlic paste before adding this ingredient. Make sure that you are working on a steady cutting board. Place a damp towel (cloth or paper) under the board to prevent it from moving around. Place garlic on the cutting board and mince. Sprinkle with the 1/2 teaspoon of kosher salt. Using the flat side of a chef’s knife, drag garlic and salt back and forth across the cutting board in small circular motions until garlic is ground into a paste. (If the salt doesn’t draw moisture out of the garlic to help it turn into a paste, you might have to add a drop or two of olive oil).
Next rub paste on the top and sides of the roast. Let rest at room temperature for 30 minutes before placing in a preheated 250 degrees F smoker.
Apply smoke until the internal meat temperature reaches 120 °F. This will take about 1 hour and 45 minutes. If you like more smoke, then smoke at 220 °F; this will extend your smoking time.
Remove roast from smoker when it reaches 120 °F, and place in a preheated 450 °F oven for about 10 minutes; until roast internal temperature is 130 °F. This will give it a nice crust. Monitor this closely; depending on your oven your roast may reach 130 °F before 10 minutes. Also you have to be careful that the rub does not burn.
Remove from oven and let rest for at least 30 minutes. During this time the roast will reach 135 °F.
To serve carve into thin slices. The leftovers can be refrigerated for up to 7 days