How to Make It
Heat a small skillet over medium. Add pepitas and toast, stirring occasionally, until beginning to pop and darken slightly, about 3 minutes. Set aside to cool 5 minutes.
Place orange zest and juice, lime zest and juice, oil, oregano, salt, pepper, garlic, and toasted pepitas in a food processor. Pulse until coarsely ground, about 20 pulses. Allow to stand at room temperature at least 10 minutes or up to 30 minutes.
Spread pepita mixture on cut sides of ciabatta rolls. Arrange cheese and arugula evenly over bottom halves of rolls and replace the top halves.
Heat a large skillet over medium. Place sandwiches in skillet and cover each with a small piece of aluminum foil. Place a separate heavy skillet on top of sandwiches and press down firmly. Cook, flipping halfway through, until rolls are toasted and cheese starts to melt, 4 to 5 minutes total. Cut sandwiches in half and serve.