In a small bowl, whisk together the mustard powder and 2 tablespoons of warm water. Add the mixture to a food processor and combine with coconut aminos, tahini, ginger, garlic, and fish sauce. Blend until smooth. Set aside.

Place the cubed chicken in a large bowl and toss with salt and pepper to evenly coat.

In a large wok or large skillet, heat the avocado oil over high heat until just smoking. Working in batches so you don't crowd the pan, add the chicken in a single layer. Sear evenly on all sides, tossing occasionally until cooked through or no longer pink and golden brown on all edges about 7 minutes. Use as slotted spoon to transfer the cooked chicken to a plate. Repeat until all the chicken is cooked.

Add the ghee to the pan. When it melts, toss the onion, mushrooms, zucchini, and carrots. Cook, stirring occasionally, until vegetables are just cooked and slightly tender ( you don't want them too soft- I like a little crunch to mine), about 4 minutes. Return the cooked chicken to the skillet and add the toasted sesame seeds. Cook, stirring, for 2 more minutes. Transfer the mixture to a plate and serve with the Magic Mustard Sauce.