In a large bowl combine the salt, lime juice and the remaining 1 teaspoon sugar. Stir until sugar has dissolved, add the sardines and allow to marinate for 10 minutes.
Within 10 minutes the sardines should be cured from the acids in the lime juice getting slightly discoloured. Gently squeeze the sardines until there is no juice dripping from them then transfer to another bowl; discard the liquid.
To the bowl with the sardines add the perilla leaves, two kinds of mint, reserved pickled onions, fried Asian shallots, fried garlic chips, garlic oil and dress with dipping fish sauce. Mix well, then transfer to a platter.
Garnish with crushed peanuts and chilli.
Yield: about 1 cup