Mahogany Marinade: Mix sugar, mustard, hoisin sauce, vinegar, and lime juice in a medium bowl. Remove 6 tablespoons for later use. Place cubed chicken in a Ziploc bag and add the remaining marinade; refrigerate for 20-30 minutes. (If making Smoky Lime Sweet Potatoes, start potatoes at this point; chicken will be ready to skewer and cook when potatoes are completed.).
Thread chicken on skewers; discard marinade. Grill skewers, basting with reserved marinade near end of cooking time.
Chimichurri Sauce: Combine cilantro and garlic in food processor. Pulse until chopped. Add oil in a thin stream with food processor running. Pulse in salt and pepper. Set aside.
To serve: Remove chicken from skewers; drizzle with Chimichurri Sauce. Sweet potatoes can also be drizzled with sauce.
Cut sweet potatoes into 1/2 inch chunks. Put in a medium saucepan; add water to cover. Bring to a boil, reduce heat, cover and cook 15 minutes or until tender. Reserve 1/4 cup cooking water. Drain potatoes, return to pan, and mash with reserved water. (I only used 2 tablespoons of reserved water.).
Add remaining ingredients and mash into sweet potatoes.