1jalapeño or serrano chile, sliced very thinly (optional)
Pinchedible flowers such as nasturtium blossom,, mustard blossom, marigold petals
Pinchground chile piquín
Extra-virgin olive oil and Maldon sea salt, to finish
Cover the bottom of a small rectangular pan with half of the salt. Place fish on top of the salt layer and cover with the remaining salt. Cover pan with plastic wrap and place in refrigerator for one hour.
To a pot of heavily salted boiling water, add the onion petals and cook for 20 seconds. Using a wire skimmer or spider, remove the onions, season with salt and submerge them in a bowl of ice water to halt the cooking process and set aside for garnish.
Using a sharp knife, slice off the top and bottom of each plum tomato. Locate the fleshy dividing wall of one segment inside the tomato. Slice alongside the dividing wall and open up the flesh of the tomato to expose the seeds. Remove the seeds and their pulp by slicing around the core of the tomato. Keep the seeds and their surrounding gel intact to create tomato seed “hearts” and set the "hearts" aside for garnish. Roughly chop the remaining outer tomato flesh.
Drain the 2/3 cup olives and remove pits. Add the chopped outer tomato flesh, the pitted olives, and lime juice to a blender and puree until smooth. Pass the mixture through a fine mesh strainer, then set aside.
Remove the fish from the refrigerator and rinse away the excess salt with water. Pat the fish dry with a paper towel. Holding a sharp knife at a 45-degree angle, cut the fish into thin slices.
Spoon the olive tomato puree onto serving dishes. With tongs, place snapper slices on top of the dressing. Add olive slivers, pickled onion slices, onion petals, capers, tomato hearts, and (if desired) jalapeño slices. Drizzle on more puree, then garnish with cilantro, nasturtium, sorrel, watercress, and edible blossoms. Finish with ground chile piquín, olive oil, and sea salt. Serve immediately.