In a hot saute pan add oil, garlic and shrimp and saute for approximately 1 minute. Add squid and mussels and simmer until mussels open. Do not allow shrimp to overcook. Season with salt and pepper. Remove shrimp if mussels are not open. Remove seafood with slotted spoon and reserve. Reduce remaining liquid to nape. Add 1 bunch watercress and deglaze with soy sauce.
Place second bunch of watercress in mixing bowl and toss with sliced red onion, tomatoes, bean sprouts, chervil, chives, champagne vinegar and salt and pepper to taste.
Plate watercress on plates and garnish with seafood around and on top. Sprinkle with crumbled feta cheese.