Marinate the steak: Combine the steak, salt, tamari, avocado oil, and coconut sugar in a large zip-top plastic bag. Shake to coat and marinate at room temperature for at least 20 minutes or in the refrigerator for up to 24 hours.

Make the zucchini noodles: Use a vegetable peeler to slice the zucchini into long, thin ribbons—I like to cut a small piece, lengthwise, off the bottom of the zucchini so it rests it flat on the cutting board, then hold it long-side down and drag the peeler toward me. Place the zucchini noodles in a strainer set over a bowl or in the sink and sprinkle with salt, tossing to coat. Let drain for at least 10 minutes or up to 30. Pat the noodles dry with a clean kitchen towel.

Heat a dry wok or large skillet over medium heat. Place the cashews in the dry skillet and toast, stirring frequently, until the smallest pieces have turned golden brown, about 3 minutes. Remove the cashews from the pan.

Return the pan to medium-high heat and add 1 tablespoon of oil. When it shimmers, add the ginger, garlic, bok choy stems, tamari, and 2 tablespoons of water, and cook, stirring frequently, for about 4 minutes, until the bok choy is crisp-tender. Add the bok choy leaves and rice vinegar and cook until the leaves wilt, 1 to 2 minutes. Push everything to one side of the pan and add the egg to the other; cook until almost set, then toss with the vegetables to combine. Transfer to a medium bowl.

Wipe out the pan, return it to medium-high heat, and add the remaining 2 teaspoons of oil. When it shimmers, add the beef, allowing the excess marinade to drip off it as you pull it out. Cook, stirring frequently, until seared on the outside and not quite cooked through, about 4 minutes. Add the zucchini noodles to the pan and toss to coat with the oil in the pan (I like to use 2 wooden spoons to do this). Spread the noodles out in the pan and let them cook for a minute or two, until they just begin to brown. Turn the heat off. Add the bok choy and egg mixture back to the pan and use your spoons to toss until the noodles are coated and all the ingredients are well distributed.

Divide the pad see ew between 2 plates and top with the toasted cashews and sriracha, if desired, to serve.