Add the rice to a fine mesh strainer and rinse, using your hands to agitate the grains, until the water runs clear. This gets rid of the extra starch so your rice isn’t mushy. Add rice to a medium pot along with 1 ½ cups water over high heat. Once the water starts to simmer rapidly, reduce the heat to low and simmer gently, covered, for about 12-15 minutes, or until the water is evaporated and rice is cooked.
In a medium bowl, mix together the cucumber, vinegar, water and salt. Set aside.
Thaw the spinach. Let cool (if using microwave) and then squeeze out the water either in a colander or wring it out in a kitchen towel. Toss with sesame oil and salt. Set aside. This is best room temp or cold so don’t worry about keeping it warm.
In a small bowl, mix together the soy sauce or tamari, sesame oil, ginger, maple syrup, and red pepper flakes (if using).
In a large skillet over medium heat, add the oil. Once hot, add white parts of the scallions and cook for 2 minutes, stirring occasionally, until softened. Add the ground beef, break it up into chunks and spread it out into one even layer. Let cook undisturbed for 5 minutes (to let the beef get browned), stirring halfway through. Continue to break it up into chunks and cook until cooked through. Tilt the pan and spoon/drain off any excess fat.
Add the soy sauce mixture and cook for 1 more minute, stirring constantly. Remove from heat and stir in half of the green parts of the scallions.
Serve beef with rice, spinach, and cucumber, and a spoonful of kimchi (if using) and top with a fried egg, remaining green scallions, sesame seeds, and sriracha (if using).