Cook brown rice in unsalted water for the amount of time specified on the package.
Cut chicken breast into 1/2 inch (1.25 cm) bite-size pieces. Set aside.
Heat 1 tablespoon (15 mL) canola oil over medium-high heat in a non-stick skillet. You can use less oil if you have a very good pan. Add chicken and stir-fry until lightly browned and just cooked through and internal temperature registers 165°F (74°C). Transfer to plate and cover to keep warm.
Prepare the vegetables by mincing garlic, shredding cabbage, cutting baby carrots and slicing mushrooms.
Whisk together tamari, Dijon mustard, sesame oil, peanut butter and warm water in a bowl. Set aside.
Add another tablespoon (15 mL) canola oil to the pan and stir-fry the minced garlic one minute. Add the rest of vegetable and continue to stir-fry until tender crisp - about 3-4 minutes.
Pour sauce over the vegetables and stir-fry an additional 2 minutes. Stir in the cooked chicken, toss and stir-fry a few minutes to heat through.
To serve, spread out cooked brown rice on individual dinner plates. Top with stir-fry. Garnish with fresh minced cilantro and sesame seeds.