Prepare the squid. Start by cleaning the squid to get rid of innards and the beak. Pat it dry with a paper towel, ensuring it's free of moisture for better grilling. Score the squid lightly with a small knife to help it absorb the marinade.

Marinate the squid. In a large bowl, combine oyster sauce and Golden Mountain seasoning sauce. Add the clean squid, tossing it to coat fully. Allow it to marinate at room temperature for 30 minutes.

Make the dipping sauce. Chop the shallots, garlic, cilantro, and Thai chilis into small pieces. Combine all the dipping sauce ingredients in a mixing bowl, adjusting the flavors with extra lime juice, fish sauce, or sugar to your taste.

Preheat and grill the squid. Set up your charcoal grill until the coals are white-hot or adjust your gas grill to medium-high heat. Place the marinated squid on the grill, cooking for 2-3 minutes on each side until they are lightly charred and cooked through.

Brush on marinating sauce. Using a brush, coat the squid with any leftover marinade as they grill, but be careful not to overcook them.

Serve. Transfer the tender grilled squid to a serving platter. Generously slather it with your zesty dipping sauce, garnishing with fresh cilantro leaves and lime wedges before serving immediately.