Cook the brown rice according to package directions and set aside to cool slightly.
Pat the ahi tuna dry with a paper towel and cut into 1/2-inch cubes.
In a medium bowl, whisk together the coconut aminos, sesame oil, lime juice, sea salt, and black pepper.
Add the cubed tuna to the marinade and toss gently to coat, letting it sit for 10 minutes in the refrigerator.
Thinly slice the cucumber, radishes, and green onion, and pit and slice the avocado.
Divide the cooked brown rice into a bowl and top with the marinated tuna, edamame, cucumber, radishes, and avocado.
Garnish the bowl with sesame seeds and sliced green onions before serving immediately.