Make the spice blend by mixing everything together in a small bowl. Take another bowl and make the dressing by stirring together the mayonnaise, garlic, parsley and gherkins. Stir through a couple of teaspoons of the spices, and set aside. In another little bowl, stir together the lime zest and Maldon, set aside.
Sprinkle the flour on a large plate and stir through the remaining spice blend.
Take a small sharp knife and carefully slice down the back of each prawn – this will allow them to open out on cooking, and mean you get more spicy flavour inside. As you slice the prawns, drop them onto the plate of flour. Once they are all cut toss them about to coat evenly, working a little of the spicy flour into the cut surfaces.
Fire up your barbecue ready for two zone grilling with the charcoal piled to one half so you can cook both directly and indirectly. This allows you to have control over the heat.
Once hot, rest the whole peppers directly over the fire and grill all over until soft and lightly charred. Slide away from the heat to keep warm.
Set a fireproof pan (no wooden or plastic handles) directly over the fire and add the butter. Once its foaming tip in the floured prawns and stir fry over a high heat until they are pink and cooked through and crispy in places.
To serve, slice the baguette though but leave top and bottom hinged together. If you like you can warm them briefly in the barbecue. Add lettuce to the base, followed by a whole pepper – I leave the stem on and just nibble around it! But cut into strips if you prefer…
Spoon a little dressing on top then scatter over the prawns and finish with a sprinkle of the lime salt. Tuck in whilst hot.
To cook inside:
Grill the peppers on a hot griddle pan, fry the prawns on the hob over a high heat, warm the baguette under the grill or in the oven.