In glass bowl, gently toss together fish, red onion, lemon juice, pepper paste, garlic and seasoning until combined. Transfer to large, resealable, plastic bag; refrigerate, turning once halfway through, until fish is opaque throughout, about 20 minutes.
Gently stir chopped cilantro into ceviche just before serving; serve on platter with sweet potato rounds. (Alternatively, divide among 4 plates.) Garnish with cilantro leaves and lime wedges.
• Serve ceviche with corn as well, if desired.
• Adjust the heat by adding additional pepper paste to taste.