Cut the cabbage lengthwise through the stem into quarters. Cut the cores from each piece. Cut each quarter crosswise into 2-inch-wide strips.
Place the cabbage in a large bowl and sprinkle with the salt. Using your hands, massage the salt into the cabbage until it starts to soften a bit. Add enough water to cover the cabbage for 30 minutes.
In the meantime, preheat a grill or grill pan on medium high heat. Season both sides of the zucchini and squash with salt and pepper; drizzle with oil. Grill on both sides until tender, about 2 - 3 minutes per side. Remove from heat, chop into chunks and set aside.
Drain and rinse the cabbage under cold water. Place in a colander and set aside to drain.
In a bowl add the garlic, ginger, sugar, sriracha, sweet chili paste, and water and stir into a smooth paste.
Gently squeeze any remaining water from the cabbage and add it to the spice paste. Mix in the grilled vegetables.
Mix thoroughly until everything is thoroughly coated and serve.