In a small saucepan, heat the soy sauce and sugar, stirring until the sugar is dissolved. Turn off the heat.
In a medium bowl, combine the hoisin, scallions, ginger, garlic, and sambal. Fold in the warm soy sauce mixture and whisk until fully incorporated. Cool fully, then coat the steaks in half of the marinade and marinate for 4-12 hours. Reserve the remaining marinade for cooking.
In a small saucepan, bring the rice, 2 cups of water and a pinch of salt to a simmer. Reduce heat to low, cover, and cook until the grains are tender, about 20 minutes.
In a blender, combine the tofu mustard ingredients and blend until smooth.
Bring a large pot of salted water to a boil for the broccoli. Prepare an ice bath by filling a large bowl with water and ice. When the water boils, add the broccoli for 2-4 minutes, until bright green and crisp-tender, then immediately transfer to the ice bath to stop the cooking process. Remove from the ice bath after 1-2 minutes.
Heat a large skillet over medium heat with 1 tablespoon canola oil. When hot, add the beef (discard the marinade) and mushrooms and quickly stir fry until the meat is medium-rare and the mushrooms are slightly softened.
Divide the rice and broccoli between plates. Top with beef and mushrooms, reserved marinade, peanuts, sesame seeds, scallions, and tofu mustard on the side.