Oyster

60 g1 oyster in shell (about 60 g; meat about 15 g)

Measured by kg in the book; no piece conversion required.

Instead of Oyster

Nothing truly replaces oyster's briny, soft shellfish character, but mussels or clams are closest.

Mussel or clam
Use the same weight of shelled meat, or about 2–3 times the weight if in shell. Cook just until they open or the meat firms; they are brinier and chewier than oyster.
Prawn
Use the same weight, peeled. They are firmer and less briny; cook 2–3 minutes only, and add a little soy sauce or lemon to mimic oyster's sea taste.
White fish fillet
Use the same weight, cut into chunks and add late so it does not flake apart. It is milder and less briny; add soy sauce or lemon and cook 3–5 minutes.

Mushroom
Use 120–150 g for 100 g oyster, sliced. Sauté until browned; add soy sauce or lemon for brininess. It cooks in 5–7 minutes, much faster than shelled oysters.
Paneer
Use 100 g for 100 g oyster, cut into cubes and shallow-fried first. It gives a firm bite but no seafood taste; add lemon and soy sauce, and simmer only 5 minutes.
Raw jackfruit
Use 150 g for 100 g oyster, cut into pieces and simmer until tender, 15–20 minutes longer. Shred slightly for a meaty texture; add soy sauce and lemon for a sea-like note.