How to Make It
Combine orange juice, lime juice, cilantro, salt, garlic, and serrano in a blender; process until smooth. Place scallops in a large glass or stainless steel bowl. Pour juice mixture over scallops, stirring to coat well. Chill, uncovered, 1 hour.
Fill a large pot fitted with a steamer basket with water to a depth of 1 inch; bring to a boil over high. Using a small melon baller, scoop out balls from sweet potatoes to equal 2 cups. Add sweet potato balls to steamer basket; cover and cook until just fork-tender, about 8 minutes. Add corn; cook until potatoes are tender and corn is just cooked but still firm, 2 to 3 minutes. Remove from heat, and let cool 5 minutes. Cut kernels from ear, discard cob, and set kernels aside.
Heat 3 tablespoons of the canola oil in a large skillet over medium-high until shimmering, 1 to 2 minutes. Carefully add ¼ cup of the basil; cook until crispy, 10 to 15 seconds. Remove basil, and drain on paper towels. Drain oil from skillet, wipe clean, and repeat with remaining 3 tablespoons canola oil and ¼ cup basil.
Add sweet potato balls, corn, and red onion to chilled scallop mixture; stir to combine. Divide mixture evenly among 6 bowls. Top with fried basil leaves, drizzle with olive oil, and sprinkle with pepper. Serve immediately.