Cook until the internal temperature of the meat registers 130ºF, 20 to 25 minutes total.
During cooking, turn the roast once and baste once or twice with the chimichurri-drippings mixture.
Remove to a cutting board and let stand for 20 minutes.
Cut crosswise across the grain into slices about ½ to ¾ inch thick, removing the string as you go.
Serve with the reserved chimichurri. The roast can also be chilled and sliced cold.
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