Bring a large pot of water to a boil. Cut the core out of the cabbage and place in the water.
Starting after about a minute, remove the cabbage leaves one at a time, so they are pliable but not completely cooked through. You should be able to gently pull the leaves off when they’re ready.
Place the cabbage on towels to dry while you make the stuffing mixture.
Add the garlic, sesame oil, mustard, tamari, ginger, lemon juice, garlic powder, salt, and pepper to a large bowl. Whisk to combine.
Place the lamb and beef in the bowl with the marinade and use your hands to loosely mix together. Sprinkle the baking soda over the meat and mix again, then gently stir in the rice.
Take a dry, cool cabbage leaf and place it in front of you. Spoon three tablespoons of the meat mixture onto the edge of the leaf, then roll up one time. Fold in the edges and continue to roll to the top of the leaf. Repeat until you run out of cabbage leaves or meat, whichever comes first.
Place the rolled cabbage in tight concentric circles in a large frying pan. Set the pan over medium heat and pour the broth over the cabbage rolls. Cover the pan and cook for 1 hour, until the cabbage is soft and slightly translucent and the meat is fully cooked.
Uncover the pan and cook for 10-15 more minutes to reduce. In the last 10 minutes, whisk together the peanut butter, lemon juice, ginger, garlic, tamari, toasted sesame oil, rice vinegar, lime juice, honey, salt, and a few turns of black pepper in a small bowl to make the peanut sauce. Taste and adjust seasonings as needed.
Serve the rolls warm with peanut sauce and a sprinkle with sesame seeds.
