Rinse the black rice under cold water and combine with water, coconut milk, and sea salt in a small pot.
Bring the rice to a boil, then reduce heat to low, cover, and simmer for 30 minutes until the liquid is absorbed.
While the rice cooks, finely mince the tender inner white part of the lemongrass stalk, the ginger, and the garlic.
Slice the chicken breast into thin strips and toss in a bowl with the minced lemongrass, ginger, garlic, tamari, fish sauce, and lime juice.
Heat avocado oil in a large skillet over medium-high heat.
Add the chicken and black pepper to the skillet and sear until golden brown and cooked through, approximately 6 minutes.
Toss in the sliced bell peppers and snap peas, sautéing for an additional 2-3 minutes until they are brightly colored but remain crisp.
Fluff the coconut black rice with a fork and serve the lemongrass chicken and vegetables over the top.