Cook the brown rice, according to your rice maker's instructions. If you don't have a rice cooker, you can make it over the stovetop using the ratio of 1:1. I like to add a splash of rice wine vinegar and a pinch of salt to my rice.

In a medium bowl, whisk together the soy sauce, ponzu sauce, sesame oil, sesame seeds and green onion. Give it a taste and adjust the seasoning, if you like. For instance, since I was using low-sodium soy sauce, surprisingly my sauce needed a pinch of salt. If you like it tarter, don't be shy to add a splash more of ponzu sauce.

Dice up the tuna into bite-sized pieces and add them to the medium bowl with the sauce. Toss until thoroughly coated. Allow to marinate for 5 minutes. To assemble, add the cubed avocado to the tuna and lightly toss. Add the warm rice to a bowl and top with the marinated tuna and avocado mixture. Garnish with the slivers of habanero and a few more pinches of sesame seeds. Serve immediately.