In a small bowl, whisk together all the ingredients for the marinade: lime juice, soy sauce, sesame oil, cilantro, green onions and cucumber. Put the salmon (or tuna) in a medium bowl and pour the marinade over it. Use a spoon to gently toss ingredients together.
Refrigerate for 15-20, depending on how "cooked" or raw you like your poké.
While the poké hangs out in the fridge make the spicy mayo by combining the mayo and sriracha in a small bowl. If you don't like a lot of spice, start with 2 tablespoons of sriracha. Keep tasting until it's the level of heat you like.
In a deep, wide heavy pot, heat 2 cups of oil over medium high heat.
When little bubbles form when you add a drop of water, add wontons. Don't overcrowd the pan, so you'll have to repeat this until all the wontons are fried. My pot easily fit 3, so you may be able to fit 2-4, depending on the size of your pot.
Fry until lightly golden brown, then use tongs to gently flip them over to fry the other side. It should only take about 1-2 minutes per side to fry the wontons. BE CAREFUL -- the oil will be hot, so use tongs and flip them away from you. If they start frying too quickly, lower the heat.
Remove fried wontons to a plate lined with paper towels.