In the bowl of a food processor, combine the peanut butter, coconut milk, soy sauce, lime juice, hot sauce, and sesame oil, and process on high speed. Add the red onions, green onions, and garlic, and process until smooth.
Place the tuna in a large bowl and toss with the peanut butter dressing. Divide among small plates. Top each portion with the chopped seaweed and chopped peanuts, and serve.
Yield: 4 to 6 servings