Marinate the Steak: Place the ribeye steak in a large resealable plastic bag. Pour in ¼ cup teriyaki marinade, seal the bag, and gently massage it to coat the steak evenly. Refrigerate for approximately 30 minutes to allow the flavors to develop.
Prepare the Cucumber: Wash the cucumber and trim off both ends. Cut it lengthwise into thick strips, then dice into small, bite-sized pieces. Transfer to a small bowl and set aside.
Dice the Mango: Stand the mango upright on a cutting board. Slice along both sides of the pit to remove the two fleshy sections. Score the flesh into small cubes without cutting through the skin. Carefully separate the cubes from the peel and place them in a small bowl.
Cut the Lime: Wash the lime and slice it into wedges. Set aside for serving with the finished bowls.
Prepare the Cilantro: Rinse the fresh cilantro and gently separate the leaves from the thicker stems. Measure approximately ¼ cup of leaves and set aside for garnishing.
Grill the Steak: Preheat a grill pan over medium-high heat. Remove the ribeye from the resealable bag and discard the used marinade. Place the steak in the hot grill pan and cook for approximately 4–5 minutes per side, depending on its thickness and your preferred doneness. Turn the steak with kitchen tongs to develop grill marks on both sides.
Rest and Slice the Steak: Transfer the grilled steak to a clean cutting board and let it rest for approximately 5 minutes. Using a sharp knife, slice the steak into thin strips against the grain to keep each bite tender.
Heat the Sesame Oil: Place a large nonstick skillet over medium heat. Add 1 tablespoon sesame oil and allow it to warm for approximately 30 seconds.
Cook the Sweet Potato Spirals: Add 4 cups sweet potato spirals to the skillet. Using kitchen tongs, gently toss the spirals to coat them evenly with the sesame oil. Sauté for approximately 5–7 minutes, stirring occasionally, until they soften slightly but still hold their spiral shape.
Add the Teriyaki Marinade: Pour the reserved 2 tablespoons of fresh, unused teriyaki marinade over the sweet potato spirals. Toss thoroughly with the tongs and cook for another 1–2 minutes, until the sauce evenly coats the spirals and gives them a glossy finish.
Build the Sweet Potato Bowls: Divide the cooked sweet potato spirals evenly between two serving bowls. Arrange the diced cucumber over the spirals, followed by the fresh mango cubes, distributing the ingredients evenly between both bowls.
Add the Green Onions: Sprinkle ¼ cup finely chopped green onions evenly over the two bowls. Their mild onion flavor adds freshness and crunch to the sweet potato spirals and fruit.
Top with Grilled Steak: Arrange the sliced ribeye steak over the sweet potato spirals, cucumber, mango, and green onions. Divide the steak evenly between both bowls.
Garnish and Serve: Finish each bowl with a generous sprinkle of fresh cilantro leaves. Serve immediately with lime wedges on the side, allowing each person to squeeze fresh lime juice over the steak and sweet potato spirals just before eating. Enjoy while warm!