To prepare the tri-tip, in a nonreactive glass bowl or a sealable plastic bag, combine the wine, olive oil, vinegar, mustard, Worcestershire sauce, soy sauce, black pepper, onion powder, salt, red pepper flakes, garlic, lemon zest and lemon juice. Add the tri-tip and turn to coat. Cover the dish or seal the bag and refrigerate for at least 3 hours or up to 24 hours.

Prepare a medium-hot fire in a grill. Remove the tri-tip from the marinade; discard the marinade.

Grill the tri-tip to medium-rare. Transfer to a carving board and let rest for 15 to 30 minutes. Thinly slice the meat on the bias, saving the jus for later dipping.  

To prepare the onion jam, peel the onions and cut into slices no larger than 1/4 inch thick. In a large sauté pan over medium-low heat, melt the butter. Add the onions and cook, stirring frequently and taking care not to burn them. Cover the pan and cook, stirring occasionally and adding the wine as needed to moisten the mixture. The jam is done when it is medium brown and the onions are very soft. Remove from the heat.

To assemble the sandwiches, place the sliced tri-tip on the roll bottoms. Top with the onion jam and blue cheese crumbles and cover with the roll tops. Serve with your favorite coleslaw and reserved jus for dipping.