Cook the pad thai noodles according to package directions until al dente. Drain and rinse with cold water to prevent sticking.
Prepare the veggie noodles: spiralize the beet and sweet potato into thin strands. If no spiralizer, thinly slice bell peppers and cut sweet potatoes into thin matchsticks.
Assemble the bowl: In a large serving bowl, combine the cooked pad thai noodles, beet noodles, sweet potato noodles, edamame, sliced bell pepper, carrot ribbons, sliced radishes, mango matchsticks, fresh basil, and roasted peanuts.
Make the dressing: In a small bowl, whisk together the sauce ingredients (tamarind paste, soy sauce, lime juice, honey/maple syrup, garlic, ginger, chili flakes, peanut butter, and water) until smooth and well combined.
Dress the salad: Pour the prepared dressing over the ingredients in the large bowl. Toss gently but thoroughly to ensure everything is evenly coated.
Finish and serve: Just before serving, add fresh spinach or watercress and toss once more. Serve immediately and enjoy the vibrant flavors!