Cook the brown rice according to package instructions and set aside to cool slightly.
In a small glass bowl, whisk together the coconut aminos, toasted sesame oil, grated fresh ginger, lime juice, and sea salt.
Using a sharp knife, carefully dice the sushi-grade ahi tuna into 1/2-inch cubes.
Place the tuna cubes into the marinade and toss gently to coat; let it sit in the refrigerator for 5-10 minutes.
Prepare the vegetables by slicing the cucumber into rounds, thinly slicing the radishes, and shelling the edamame.
Assemble the bowl by placing the cooked brown rice at the base, followed by the marinated tuna.
Arrange the cucumber, radishes, edamame, and sliced avocado on top of the rice.
Garnish the entire bowl with black sesame seeds and serve immediately while the tuna is chilled.