Bring two cups of water to a bowl in a medium saucepan. Once boiling, whisk in the bullion and remove from heat (you should have bullion measured for 4 cups of broth, but you are only using half of the water). Once all of the bullion has dissolved, add the soya chunks and let sit for at least 15 minutes.
Whisk all of the sauce ingredients together and set aside.
Once soya chunks have rehydrated, strain them from the broth and add them to a medium-sized bowl. In a small bowl or ramekin, combine the cornstarch, onion powder, garlic powder, sea salt, ginger powder, and pepper. Sprinkle mixture over the soya chunks and toss to coat evenly.
Heat a medium to large skillet to medium heat and drizzle with oil. Once the oil is hot, add the soya chunks and sautée until browned. Remove from heat.
Heat a large, deep skillet to medium heat and drizzle with oil. Once hot, add the yellow onion, the whites of the green onions, the bell pepper, garlic, and ginger. Sautée for 3 - 5 minutes, until onions have softened. Add the green beans, zucchini, celery, and sauce, then stir. Continue to cook on medium heat, stirring occasionally, until the veggies start to soften and the sauce has thickened. Stir in the water chestnuts, half of the greens of the green onions, 3/4 cup of the cashews, and the soya chunks. Once the soya chunks are reheated remove from heat.
Chop the remaining 1/4 cup of cashews and use as a garnish with the remaining green onions.