Add the saffron to a shot glass and infuse with a table spoon of hot water (not boiling), and leave to one side.
Slice 1 clove of garlic and place in a cold pan with 2 table spoons of olive oil. Over a medium heat cook until the garlic slides are nice a golden, then remove from the pan.
Add the prawns and fry for a minute or so until they are cooked, then remove the prawns and set to one side. If there is any liquid from the prawns, add this garlicky oil to the fish stock.
Chop the onion into cubes and fry with the remaining 2 table spoons of oil. Fry on a medium heat until they go translucent.
Crush the remaining garlic and add to the onions. Fry for another minute.
Add the paprika and fry for 30 seconds.
Add the chopped tomatoes and cook until the water has been evaporated. Stir often to prevent the tomatoes from catching on the bottom of the pan.
Add the paella rice and stir through to ensure that all grains are coated with the concentrated "sofrito".
Add the fish stock, then stir the rice round gently to ensure that it is evenly distributed along the bottom of the pan. There will be no more stiring after this stage.
Increase the heat for the stock to boil away for about 10 minutes . By this stage, the rice will begin to show through the surface of the stock.
Turn the heat down to a medium heat and arrange the prawns over the top of the paella. Cook for another 8-10 minutes.
Once the stock has almost been completely absorbed by the rice, you can turn the heat off and cover with foil for 10 minutes. The rice will continue to cook and absorb the stock with the residual heat in the pan.
Serve at the table with a lemon wedge.