In a small bowl, add the olive oil, balsamic vinegar, lemon juice, pinch of salt and freshly ground pepper; mix until thoroughly combined. Do a taste test and add a bit more salt, if you like. Set aside.
Sprinkle the figs with the dark brown sugar and a pinch of salt. Heat a grill or grill pan. When hot, brush with olive oil. Place the figs on the hot grill, face down and cook for 1-2 minutes, until grill marks appear. Remove and set aside.
To a large mixing bowl, add the arugula. Sprinkle the leaves with salt. Add half of the dressing and lightly toss the salad. Transfer the lettuce to your serving plate. Add the peaches to the mixing bowl and toss with a bit of dressing. Transfer the peaches and figs to the serving plate, arranging how ever you like. Top with a sprinkling of pistachios, a few torn pieces of prosciutto and thin slices of ricotta salata.