Put
the shrimps in a shallow dish. Sprinkle over the
salt, ginger and cornstarch and rub them into the
flesh with your finger.
Heat
the oil a large frying-pan. When it is hot, add the
shrimps and fry for 2 minutes, stirring constantly.
Remove from the heat and using a slotted spoon,
transfer the shrimps to a plate. Cover and keep hot.
Pour
off the oil from the pan and return to the heat. add
the butter and melt it. When it has melted, add the
tomato quarters and fry for 2 minutes, stirring
constantly. Stir in the soy sauce and tomato paste
and cook for a further 30 seconds.
Combine the cornstarch, stock, wine for sherry and
sugar. Pour the mixture into the pan and cook,
stirring constantly, until the sauce thickens and
becomes translucent. Return the shrimps to the sauce
and baste well. Cook for a further 1 1/2 minutes,
stirring constantly.
Transfer the mixture to a warmed serving dish and
serve at once.