Place diced sweet potatoes in a microwave-safe bowl, sprinkle with 1 teaspoon of salt, and cover with a plate. Microwave on high for 4-6 minutes, stirring halfway through, until just tender. They should offer slight resistance when pierced with a knife. Avoid overcooking to prevent mushiness.

Heat a 12-inch skillet over high heat and add 2 tablespoons of olive oil, heating until shimmering. Add steak pieces in a single layer and cook, turning every two minutes, until browned and medium-done in the center, about 10 minutes. Transfer the steak to a plate with a slotted spoon.

Add another tablespoon of olive oil to the skillet. Toss in the sweet potatoes and cook, stirring occasionally, until browned, about 3-4 minutes.

Create a small space in the center of the pan and add the garlic, cooking until fragrant, about 1 minute.

Add bell pepper to the potatoes, tossing occasionally until the peppers are just tender, about 3-4 minutes.

Return the steak and its juices to the pan, add soy sauce, and toss everything together. Cook for an additional 1-2 minutes until the liquid has evaporated.

Stir in pepper and cilantro, remove from heat, and serve immediately. Optionally, garnish with more fresh cilantro.