In a medium bowl, stir together half the green onions, the soy sauce, sugar, and crushed red pepper. In a large skillet heat oil over medium-high heat; add ginger and garlic and cook until fragrant, about 30 seconds. Stir pork into the garlic and ginger, and then press flat to make one large patty. Cook 3 to 4 minutes without stirring. When pork is browned and crisp on bottom, break up the patty and stir in the soy sauce mixture, reserving the bowl. Stir until pork is completely cooked and crumbled, 2 to 3 minutes more.
In the reserved bowl, combine the remaining green onions, cucumber, and herbs. Spoon pork mixture over rice and top with cucumber salad. Serve with lime wedges and/or Sriracha sauce, if desired.