Cook the rice: Add the rice and water to a pot over high heat with a pinch of salt and bring it to a boil. Then cover and reduce heat and let it simmer for 10 minutes, then turn off the heat and let the rice steam. No peeking or stirring!
Cook the beef: Add 1 TBSP olive oil to a skillet over medium heat. Add the beef with a pinch of salt and cook, stirring often, for 8-10 minutes, until the beef is no longer pink. Drain the pan and add the sriracha, chili garlic sauce, soy sauce, brown sugar, fish sauce, and oyster sauce to the beef. Stir well and cook over medium heat for about 5 more minutes. Turn off the heat and set the beef aside.
Prepare the cucumber: toss the sliced cucumber with rice vinegar, sugar, and red pepper flakes with a pinch of salt. Set aside.
Prepare the spinach: heat up the same pan you used to cook the beef. Add the olive oil and spinach with a pinch of salt. Saute over medium-low heat until it has completely wilted, about 6-8 minutes. Covering the pan helps steam spinach nicely. Turn the heat off and add the sesame oil. Gently toss to coat the spinach. Set aside.
Assemble! Divide the rice and beef between three meal prep containers. Garnish with sesame seeds if using. In another container or in a few small containers, store the carrots, cucumber, spinach, and kimchi. I stored the spinach with the meat and rice because it was cooked and would taste good warm. When ready to eat, cook the egg to your preference (sunny side up is ideal! boiled works too) and add the other prepared toppings to your bowl.