Cook the rice noodles according to package directions, drain, and run under cool water to cool down. If the noodles are sticking together, add a tiny bit of sesame oil and toss them in it.
While you're waiting for the noodles to cook, add the sunflower seed butter, juice, vinegar, coconut aminos, sesame oil, honey, ginger, and garlic to a food processor. Blend until totally smooth and creamy. Taste and add kosher salt and pepper, as needed. (This will vary as some sunflower seed butters are more salty or sweet than others). Set aside to let the flavors meld together, about 30 minutes.
Place the cooled noodles in a large bowl with slaw, chopped bell pepper, cilantro, basil, and radish. Chill everything for 30 minutes while you wait for the dressing to develop some flavor. Then add the dressing a little bit at a time, tossing everything together until it's dressed to your liking (you may have some leftover). Serve cold with sriracha and/or sweet chili sauce on the side.
This salad will keep in the fridge for 2 days.