For the caramelized onions: Heat a nonstick skillet over medium heat. Add the olive oil and onions, separating them, and sprinkle with the salt. Saute for 10 minutes, then turn down the heat to medium-low and cook until the onions are deep amber in color, another 35 to 40 minutes. You can either buy your fig jam in advance or make your own: combine 1/4 cup water, the figs, sugar and lemon zest in a saucepan and simmer over low heat until thick, 45 to 60 minutes. Put it all together: Spread 1 tablespoon jam on each of 4 slices of toast and add 1 tablespoon caramelized onions. Put in panini maker or into greased frying pan and cook on both sides until cheese is melted and bread is toasted.