Make the burger sauce by whisking together all of the ingredients until thoroughly combined. Place in the fridge while you make the beef.
Heat a large skillet over medium high heat and add the avocado oil. Add the onion and cook for 2-3 minutes until fragrant. Add the garlic and cook for another minute.
Add the ground beef and cook for about 5-7 minutes until cooked through. Add a pinch of salt and pepper and the mustard. Stir and remove from the heat.
To assemble the burger bowl, place a large handful of mixed greens into your bowl. Follow with some of the ground beef mixture, red onion, avocado, cheese, pickles, and tomatoes. Drizzle with a bit of the burger sauce to top. Sprinkle with sesame seeds to finish.