Wash the green onions and pat them dry with paper towels. Trim off the roots, slice each entire stalk lengthwise, and cut into 2-inch-long pieces.
Pat the shrimp and squid rings dry with paper towels to remove excess moisture.
In a large mixing bowl, whisk together the all-purpose flour, potato starch, baking powder, garlic powder, onion powder, chicken bouillon powder, and salt until evenly combined.
Add the green onions, shrimp, squid rings, and very cold water to the dry ingredients. Mix just until combined, making sure everything is coated in batter. Avoid overmixing.
Heat 2 1⁄2 tablespoon of vegetable oil in an 11-12-inch nonstick pan over medium-high heat, swirling the pan to evenly coat the bottom. Add the batter and spread it evenly across the pan, scraping out any remaining batter from the bowl to fill any gaps. Reduce the heat to medium and fry for about 5-7 minutes until the bottom is golden brown and crispy, and the green onions are lightly charred. Occasionally swirl the pancake in the oil to help it brown evenly.
Once the bottom is firm, carefully flip the pancake using a large, wide spatula. Pour the remaining vegetable oil around the edges and swirl the pan to distribute it underneath. Gently press down on the pancake with the spatula and fry for about 4-5 minutes until both sides are golden brown and crispy, and the seafood is cooked through.
Transfer the pancake to a cutting board and slice into square pieces.
Then mix all the dipping sauce ingredients together in a small bowl and serve the sauce with the hot pancake.