Cook the Shrimp: Begin by heating a large nonstick or cast-iron skillet over high heat. Add olive oil, followed by the shrimp, seasoning them with salt and garlic powder. Stir occasionally until the shrimp turn golden and opaque, about 2 to 4 minutes. Once cooked, transfer the shrimp to a plate and set aside, leaving behind the flavorful oil in the pan.
Sauté the Vegetables: In the same skillet, add the diced onion and mixed vegetables, cooking them for 1 to 2 minutes until the onion softens but retains a slight crunch, and the vegetables are mostly thawed. Add the rice and soy sauce, stirring occasionally. Continue cooking until the rice is well-mixed and begins to crisp on the bottom, 5 to 7 minutes. Taste and adjust the seasoning with additional soy sauce as needed.
Scramble the Eggs: Push the rice mixture to one side of the pan and lower the heat to medium. On the empty side, melt the butter, then crack the eggs into the pan. Stir vigorously to scramble the eggs, cooking them until they are just set but remain soft and tender, about 1 minute. Incorporate the scrambled eggs into the rice, then add the reserved shrimp and any juices that have accumulated. Remove the pan from the heat.
Crisp and Serve: Let the fried rice sit for a few minutes, allowing it to crisp further in the pan's residual heat. If you’re preparing a side of yum yum sauce, now is the ideal time to make it. Drizzle the sauce over the fried rice in the skillet, leaving some on the side for dipping the shrimp if desired. Serve hot.