Roast beef is a weekly tradition in Colombian homes. This is a simple way to cook this dish without the stove top and the mango sauce is a delicious accompaniment.
Process cilantro, scallions, brown sugar, garlic, bay leaves, pepper, and ají or hot pepper, if using, to make a paste. Rub beef with mixture and refrigerate overnight.
PREPARE MANGO SAUCE: In a blender, purée mango, cilantro, vinegar, honey, salt, and pepper. Gradually add olive oil in a stream until blended. Set aside.