Tri Tip and Caramelized Onion Sandwiches With Mustard Aioli

Tri-tip sandwich with caramelized onions
Sabrina S. Baksh/Regarding BBQ, Inc.
Prep: 20 mins
Cook: 33 mins
Total: 53 mins
Servings: 5 servings

These tri-tip sandwiches are perfect for any kind of game night, cookout, or family dinner. The caramelized onions are a great accompaniment to the steak; however, the mustard aioli really ties it together. This will quickly become one of your favorite sandwiches.


  • 4-5 tri-tip steaks (about 1.5 pounds/700 g)
  • 1/4 cup/60 mL olive oil
  • For Marinade:
  • 2 teaspoon/10 mL apple cider vinegar
  • 2 teaspoons/10 mL Worcestershire sauce
  • 1 1/2 to 2 teaspoons/7.5 to 10 mL salt (sea)
  • 1 1/2 teaspoons/7.5 mL onion powder
  • 1/2 teaspoon/2.5 mL chili powder
  • 1/2 teaspoon/2.5 mL black pepper (coarse ground)
  • For Onions:
  • 2 onions (sliced into 1/2 inch rounds)
  • 3/4 cup/180 mL stock (beef or chicken)
  • 2 tablespoons/30 mL olive oil
  • 2 teaspoons/10 mL red wine
  • 1 teaspoon/5 mL Worcestershire sauce
  • 1 teaspoon/5 mL salt (sea)
  • Black pepper to taste
  • For Mustard Aioli:
  • 1/2 cup/120 mL mayonnaise
  • 1 tablespoon/15 mL mustard (stone ground or Dijon)
  • 1/2 teaspoon/2.5 mL chili powder
  • 6 hamburger buns
  • 6 slices Swiss cheese

Steps to Make It

  1. Place steaks in a resealable plastic bag. Combine marinade ingredients, and pour over steaks. Make sure to work marinade well into the meat. Seal bag, and place into the refrigerator for 2 hours. 

  2. Preheat grill for medium-high heat. While the grill is heating up, slice onion, and heat olive oil in large skillet on the stove. Add onion, salt, and black pepper. Allow the onion to cook on high for 2 minutes, reduce heat to medium-low, and cook for 5 minutes, turning often. Add wine and Worcestershire sauce, let cook for 2 to 3 minutes. Add stock, reduce heat to low, and cook for 15 minutes.

  3. Place steaks on the grill, and cook for 10 minutes turning often. Steaks should cook quickly since they are relatively small and thin. If they are thicker, leave on for an additional 2-3 minutes. Remove from heat, and place onto the cutting board. Allow meat to rest for a few minutes before slicing.

  4. Prepare aioli by combining mayonnaise, mustard, and chili powder. If making ahead of time, place into an airtight container, and store in the fridge for up to 2 days after preparation.

  5. To assemble, place Swiss on the lower bun, add 6 to 8 slices of meat, 1/4 cup/60 mL of caramelized onion, and spread a generous amount of aioli on remaining inside half of the bun before topping sandwich.