Brush tri-tip with olive oil and season with salt and pepper. Heat grill to medium-high. Cut ciabatta into six equal pieces and slice open. Brush inside of bread with olive oil and sprinkle with salt and pepper. Mix the garlic, mayonnaise and ¼ cup olive oil to make the aioli. Salt and pepper to taste. Put tri-tip on heated grill and cook 20 minutes or until a meat thermometer reads 135-140 degrees. Remove meat, cover with foil. While meat is resting grill the ciabatta slices until toasted. Slice the tri-top across the grain, about ½ inch thick. To make sandwiches slather top and bottom slices of bread with a tablespoon each of aioli, top with 2 or 3 slices of beef, then place a small handful of arugula over meat and close with top piece of bread. Serve with a glass of Bruce Patch Zinfandel. Serves 6.