Soak cashews in hot water for 30 minutes. Drain and blend with 1 jalapeño, lime juice, water, garlic powder, and salt until smooth. Set aside.
In a bowl, combine chicken thighs, olive oil, sazon seasoning, cumin, smoked paprika, garlic powder, salt, and pepper. Mix well to coat.
Grill or sear chicken over medium-high heat for 5-7 minutes per side until internal temperature reaches 165°F. Rest for 5 minutes, then slice into strips.
Char corn kernels in a dry skillet over high heat until dark spots form, about 5-7 minutes. Transfer to a bowl.
Add diced avocado, red onion, 1 minced jalapeño, cilantro, and lime juice to the corn. Season with salt and pepper. Mix gently.
Warm tortillas in a dry skillet for 30 seconds per side. Assemble tacos with sliced chicken, street corn salsa, and cashew sauce.
Top with cotija cheese, extra cilantro, and lime wedges. Serve immediately.