In a blender, combine garlic, soy sauce, lime juice, olive oil, cumin, paprika, oregano, and black pepper. Blend until smooth.

Place chicken thighs in a Ziploc bag and pour marinade over. Seal and refrigerate for 8 to 24 hours.

In a clean blender, blend jalapeños, cilantro, green onions, garlic, mayonnaise, Greek yogurt, lime juice, salt, and black pepper until smooth. Drizzle olive oil while blending.

Preheat grill to medium-high heat, and grill chicken thighs for 5–6 minutes on each side, until cooked through.

Let chicken rest after cooking, then serve with aji verde sauce on the side.