Cut the sushi-grade ahi tuna into uniform 1/2-inch cubes and place them in a chilled glass bowl.
In a small ramekin, whisk together the coconut aminos, toasted sesame oil, and freshly grated ginger.
Pour the marinade over the tuna cubes and toss gently with a spoon to coat; let it sit in the refrigerator for 10 minutes.
Prepare the tropical salsa by combining the diced mango, diced pineapple, minced red onion, chopped cilantro, and lime juice in a separate bowl.
Scoop the warm, cooked brown rice into the center of a wide serving bowl as the base.
Arrange the marinated tuna, tropical fruit salsa, shelled edamame, sliced cucumbers, and thinly sliced radishes in distinct sections over the rice.
Finish the bowl with a light sprinkle of sea salt and serve immediately while the tuna remains cold.