Gather all the ingredients.
Use a blender or food processor to blend ingredients (1/2 onion, garlic, jalapeno, soy sauce, water, sweetener, toasted sesame oil and black pepper together to form marinade. Transfer marinade to a zip-lock bag.
Add in sliced beef and massage in the marinade ensuring equal distribution. Place zip-lock bag flat in the fridge for 24 hours (up to 36 hour flipping over at least once half way through the marinate.
After marination is complete, add 1 tbsp of cooking oil to a large fry pan and bring up to temperature on high, should take around 1 minute. Once up to temp, transfer beef only and cook for about 3-4 minutes while occasionally mixing until browned. Transfer to holding plate.
Preheat oven to 425F. Note - if using regular tortilla or shell, skip to step 10).
Line a baking sheet with a silicone baking mat (parchment paper works too). Place 1/4 cup of shredded cheese on the silicone baking mat and spread cheese around to form a circle roughly 2-3 inches in diameter. Repeat with rest of the 11 shells (or how many ever you have room for) and ensure they are not touching each other.
Once the oven reaches temperature, bake in the center of the oven for 7-8 minutes until edges have begun to brown.
Pull the tray from the oven and let cheese shells cool down for about 1-2 minutes. After cooled, transfer cheese shells to a serving plate. Top with beef, chopped onions, green onions, cilantro and a squeeze of Sriracha. To enjoy, fold cheese shell like a taco shell.