Sauté the onions in oil until tender and add the garlic and curry powder lightly sauté (don't brown the garlic).

Add the chicken stock and tomatoes and simmer for a couple of minutes.

Season prawns with salt and pepper and dust with flour.

Lightly saute the prawns in oil and add the other mixture and simmer a couple of minutes.

If you want a thick sauce it can be thickened with cornstarch.