Pulse the broccoli stems in a food processor until they break down into pieces about the size of a grain of rice, and then transfer to a medium saucepan.
Add 1/2 cup water, 1 tablespoon oil, 1 teaspoon salt and several grinds of pepper.
Bring to a simmer over medium-high heat and cook, stirring frequently, until the mixture is bright green, about5 minutes.
Put the broccoli florets on top of the broccoli rice, reduce the heat to low, cover and let steam until the florets and the rice are tender but still bright green, about5 minutes.
Remove from the heat and keep warm.
Meanwhile, whisk together the liquid aminos, orange juice, arrowroot starch/flour, sesame oil, chile flakes, garlic, and ginger in a medium bowl until smooth.
Heat the remaining 1 tablespoon oil in a large skillet over medium-high heat.
Add the chicken and cook, undisturbed, until it's light golden brown on the bottom, about 2 minutes.
Pour in the orange juice mixture, and cook, stirring, until thickened and bubbly, and the chicken is cooked through, 4 to 6 minutes. Add a splash of water to thin out the sauce if needed.
Adjust seasoning with more salt and pepper.
Divide the broccoli florets and rice among shallow bowls and top with the chicken and sauce.
Sprinkle with the scallions and sesame seeds.