Rinse the rice under cold water until the water runs clear to remove excess starch. Combine the rice with the appropriate amount of water in a pot or rice cooker. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes (or according to package instructions). Once done, fluff the rice with a fork and let it cool slightly. Optional: stir in a splash of rice vinegar for a sushi-rice flair.

Open the tuna cans and drain the water completely to avoid soggy bowls. In a medium mixing bowl, flake the tuna with a fork. Add the mayonnaise (or Greek yogurt), Sriracha, soy sauce, and sesame oil. Mix thoroughly until the tuna is well-coated and creamy. Taste and add more Sriracha if you prefer extra heat.

While the rice cools, prepare your fresh components. Dice the cucumber into small, bite-sized cubes. Shred the carrots using a grater or buy them pre-shredded to save time. Slice the green onions thinly, using both the white and green parts. Keeping these vegetables fresh and crisp provides a necessary texture contrast to the creamy tuna.

Line up four airtight meal prep containers. Divide the cooked rice evenly among the containers. Top one side of the rice with a generous scoop of the spicy tuna mixture. Arrange the cucumbers and shredded carrots in the remaining space. Garnish with sliced green onions and a sprinkle of sesame seeds. Seal the containers and refrigerate.