In a medium bowl whisk together the ponzu sauce, soy sauce, fresh grated ginger, garlic, sesame oil and red chili flakes. Add the shrimp to the bowl and toss well to coat. Place the bowl with the shrimp in the refrigerator and allow the shrimp to marinate for 30 minutes to 1 hour (or as much time as you can allow- not exceeding 1 hour). Meanwhile, prepare the vegetables.
Heat a large Dutch oven or wok over medium high heat. Add the oil. Add the shrimp to the pan in a single layer (reserving the sauce) and cook for 2 minutes, or until cooked on that side. Flip to the other side and cook for an additional 1-2 minutes more. Transfer shrimp to a clean plate or bowl when completely cooked. Repeat with any remaining shrimp. Set the shrimp aside.
To the same pan over medium high heat add 1 teaspoon of oil. Add the red and green bell pepper and cook for 2-3 minutes, stirring occasionally. Carefully add the remaining marinade to the pan and bring to a low boil. Allow the marinade to simmer for 3-4 minutes, or until liquid has reduced by half. Meanwhile fill each serving bowl with cooked rice and slice your avocado, if desired.
Once liquid has reduced, stir in the edamame, chopped green onion and the spinach. Allow them to cook until just starting to wilt, approximately 30 seconds. Finally, stir in the rainbow chard and cook for approximately 1 minute, stirring constantly. Add the shrimp back to the pan and remove from heat. Continue to stir a few more times, or until fully combined.
Divide the greens and the shrimp between the bowls and top with additional cilantro, green onion, sliced avocado, Sriracha and sesame seeds, if desired.