If your prawns have heads on remove them. (Store them in a zip lock bag in the freezer. You'll thank me next week!)
Place a large pan on the hob and add about 700ml of water and the juice from the lemon. (see notes)
Bring the water to the boil and then place a steamer or colander over the water.
Add the shrimp and sprinkle them with 1 tablespoon of the old bay seasoning.
Add a lid and steam the shrimp for 3 minutes.
Remove the lid and give the shrimps a stir. Place the lid back on and cook for a further 2-3 minutes until the shrimp are a beautiful orange colour. (The exact time will depend on the size of your shrimp)
Remove the steamer/colander from the pan and sprinkle over the remaining seasoning.
Toss the shrimp so they are all well covered.
Enjoy the shrimp hot or cold.
Just make sure you keep all the shells. (Just stick them in the zip bag with the heads. All will become clear I promise x)
For the cocktail sauce.
Mix together the ketchup, mayonnaise and the old bay seasoning. (Yup that's it ;-) )
Notes
You want enough water to ensure the pan won't dry out during steaming, but not so much that the bottom of your steamer/colander is under water.