In a small bowl, whisk together the tamari, toasted sesame oil, lime juice, grated ginger, and minced garlic to create the marinade.
Season the chicken breast with sea salt and black pepper, then coat with half of the marinade; let it sit for 10 minutes.
Heat a grill pan or outdoor grill over medium-high heat and cook the chicken for 5-6 minutes per side until fully cooked and slightly charred.
While the chicken rests, prepare the base by placing the cooked brown rice in a bowl.
Arrange the sliced cucumber, shredded carrots, shelled edamame, and sliced avocado on top of the rice.
Slice the grilled chicken into thin strips and add it to the bowl.
Drizzle the remaining marinade over the entire bowl and garnish with sesame seeds before serving.