To prepare the piadina with ham, pecorino, and tomatoes, start by making the herb salt: place the coarse salt, peppercorns, and the stripped leaves of the thyme and rosemary into a blender or food processor. Blend until finely ground and uniform.
Thinly shave the pecorino cheese and set it aside.
Remove the stems from the tomatoes and slice them lengthwise into rounds approximately 1 cm (about 1/3 inch) thick.
Heat a non-stick skillet over medium-high heat and sear the tomato slices on both sides.
Transfer the seared tomatoes to a bowl and season them with extra virgin olive oil and the prepared herb salt.
Warm the piadinas in a dry skillet over medium heat for about 1 minute per side. Place the shaved pecorino cheese over one half of each piadina so the cheese melts slightly.
Assemble the filling: arrange the mixed greens over the half with the cheese, then layer the cooked ham and roasted tomatoes on top.