In a large bowl, whisk together soy sauce, rice vinegar, sesame oil, ginger, red pepper flakes, green onions, and sesame seeds. Add tuna and toss to coat. Refrigerate for 15 minutes to an hour.
To serve, add rice to the bottom of four bowls. Top with tuna and toppings of your choice. Garnish with green onions and sesame seeds before serving.
*To the marinade, I tend to add a little bit of siracha and fresh lime juice
*To customize the bowls, you can change the base to things like udon noodles, zucchini noodles, or mixed greens for a salad. Add whatever toppings you like! I usually add a little crispy garlic, chili oil, and furikake seasoning to mine.
*Protein options - this recipe is really easy to swap other protein options in. Sushi grade salmon, cooked chicken, tofu, or more fresh veggies.