In a medium bowl, combine the pecans with the water and liquid aminos. Soak for 3 hours, then drain.
Make the pico de gallo: In a medium bowl, combine the tomatoes, onion, cilantro, garlic, salt, pepper, and lime juice and mix well. Set aside until ready to serve the tacos.
Slice the mango flesh off of the pit, then cube. Set aside.
Add the drained pecans to a food processor with the mushrooms, green and red bell peppers, red onion, jalapeño, taco seasoning, garlic and herb seasoning, and lime juice. Pulse a few times until the mixture is well chopped and resembles ground meat. Do not over-process.
Serve the pecan “meat” in butter lettuce leaves. Top with pico de gallo, jalapeño, mango, cilantro, avocado, lime juice, and Tajín seasoning.