Special equipment: a deep fryer or deep skillet; a deep fry thermometer
For the donair sauce: Combine the sweetened condensed milk and vinegar in a bowl and whisk vigorously. Slowly add the garlic powder and then the sugar and continue to whisk until all the powder has blended into the sauce. Immediately place in the refrigerator, covered plastic wrap for at least 1 hour.
For the crab and hot sauce: Shuck the crab out of the shells and place into a large bowl. Squeeze the meat tightly to remove as much liquid as possible.
Finely chop the green onions and add to the bowl with 3 of the eggs and juice from 1 of the lemons. Mix the crab meat together and form into 8 small cylindrical crab cakes.
Place the flour in a shallow bowl, the remaining 3 eggs (whisked), in another bowl, and the breadcrumbs in a third bowl. Dip each crab piece in the flour, then the eggs, and then the breadcrumbs, in that order. Place on a baking sheet and refrigerate until ready to fry.
Use a sharp knife to remove the peel and pith from the remaining lemon. Cut the flesh into quarters and combine it with the ginger, garlic and a touch of canola oil in a food processor. Blitz until broken down. Add the Scotch bonnet chiles and rice wine vinegar and continue blending all the ingredients. Add about 1/2 cup of the canola oil, the salt and a pinch of sugar until the sauce thickens up. Place in the refrigerator until ready to use.
For the salsa: Heat a grill to high heat. Roast the corn in the husks, turning occasionally, until tender and bright yellow, about 12 minutes. Alternatively, shuck the corn and boil the ears in a pot of water until tender and bright yellow, about 8 minutes. Let cool, and then carefully slice the kernels off the cob into a bowl. Finely chop the tomatoes and red onions and add to the bowl with the corn kernels. Combine the cilantro and garlic in a blender and blitz with a splash of canola oil and pinch of salt until finely chopped. Stir it into the finely chopped vegetables.
To serve: Fill a deep fryer to the maximum oil line with the remaining canola oil and heat it to 350 degrees F. Alternatively, fill a deep skillet with 2 inches of oil and heat it to 350 degrees F. Lightly fry each crab cake in the canola oil until cooked. Place a bed of salsa on each pita, top with a crab cake and a heaping spoonful of donair sauce and the hot sauce.