Since most of us are not able to have an Argentinean spit-roast lamb party in our backyard, Vera of Magnificent Moments found a comparable beef barbecue recipe with spice rub and chimichurri sauce at epicurious.com.
Thank you Vera!

Ingredients

Spice rub:
2 tablespoons dark brown sugar
1 tablespoon sweet smoked paprika or regular paprika
1 tablespoon coarse Kosher salt
1 1/2 teaspoons chipotle chile powder or ancho chile powder
1 teaspoon ground black pepper

Chimichurri Sauce I
This garlicky sauce from Argentina is great spooned over beef or chicken.
Serving size measures about 1 cup. Just about every family has its own secret recipe.

1 cup (packed) fresh Italian parsley
1/2 cup olive oil
1/3 cup red wine vinegar
1/4 cup (packed) fresh cilantro
2 garlic cloves, peeled
3/4 teaspoon dried crushed red pepper
1/2 teaspoon ground cumin
1/2 teaspoon salt

Preparations:
Puree all ingredients in processor. Transfer to bowl. (Can be made 2 hours ahead. Cover and let stand at room temperature.)

Chimichurri Sauce II
3/4 cup olive oil
3 tablespoons Sherry wine vinegar or red wine vinegar
3 tablespoons fresh lemon juice
3 garlic cloves, peeled
2 medium shallots, peeled, quartered
1 teaspoon fine sea salt
1/2 teaspoon freshly ground black pepper
1/2 teaspoon dried crushed red pepper
3 cups (packed) stemmed fresh parsley
2 cups (packed) stemmed fresh cilantro
1 cup (packed) stemmed fresh mint

Spice Rub
Combine all ingredients in a small bowl or jar a couple of days ahead of the BBQ and let the flavors mingle

Chef One:
Preheat barbecue to high heat

Chef Two:
Wash beef and pat dry meat; brush with oil; and sprinkle with spice rub. Coat the meat with all of the mixture.

Chef One:
Place beef on grill and sear from all sides. Then reduce the heat to medium-high and grill uncovered until thermometer registers 130 F (for medium-rare) inserted into the thickest part of the beef. This can take about 40 minutes. To prevent burning, move the meat to a cooler part of the grill and turn from time to time.

Transfer to platter, cover with foil, and let rest for 15 minutes.

Chef Two:
Prepare chimichurri
Combine first 8 ingredients in blender; blend until almost smooth. Add 1/4 of parsley, 1/4 of cilantro, and 1/4 of mint; blend until incorporated. Add remaining herbs in 3 more additions, pureeing until almost smooth after each addition. 

Bon Appetit!