Add the ginger, ground black pepper, chili powder, salt, and red pepper flakes in a small bowl and mix to combine. Set aside.
Pat the chuck roast dry with paper towels, then season on all sides with a sprinkling of kosher salt.
Heat a large cast iron skillet or dutch oven over medium heat, then add the oil. When the oil is shimmering, carefully place the meat in the pan. Cook for 4 to 5 minutes, until a crust has formed, then flip over and cook for another 4 to 5 minutes. Remove the meat and place in the slow cooker.
In the same skillet or dutch oven, add the sliced onions and cook until lightly browned, stirring often to pick up any brown bits, 4 to 6 minutes. Transfer to the slow cooker bowl.
Add the carrots, garlic, beef broth, coconut aminos, honey, sriracha, and spice mix to the slow cooker and gently mix together. Cover the slow cooker and set to high for 4 to 5 hours or low for 8 hours.
After the roast is done cooking, remove the lid and turn off the heat. Add the lime juice. Use two forks to shred up the roast (it should shred very easily). Serve over cooked rice, spooning the liquid from the slow cooker on top, and garnish with sesame seeds and chopped cilantro.
