Since we used shrimps that were already shelled and deveined, “400 grams” is the shelled weight. If using whole shrimps with heads and shells that you will discard, allot six to eight large shrimps, or eight to ten medium shrimps, per person.We mix our own Cajun seasoning but store-bought is quite okay to use. Two to two-and-a-half tablespoons should be fine.