For the mustard fruit: Combine the wine, sugar, vinegar and salt in a saucepan and bring to a boil. Stir in the mustard, mustard seeds and pears. Place the dried fruit in a quart-size glass jar and top off with the hot liquid and pears. Store in the refrigerator for at least 2 days and up to 1 month.
For the pork: Whisk together the cilantro, mustard, coriander, cumin, salt, paprika, lime juice and lime zest. Coat the tenderloins in the marinade and transfer the pork and marinade to a resealable plastic bag or shallow baking dish, covered with plastic wrap. Let marinate for 30 minutes at room temperature, or up to overnight in the fridge.
Preheat the grill, preferably charcoal, over medium-high heat.
Grill the pork until just under medium, 3 to 4 minutes per side. Set aside to rest for 7 to 10 minutes.
Dress the arugula lightly in the olive oil. Slice the pork and arrange on a plate. Remove 1/2 cup of the mustard fruit from the liquid with a slotted spoon and spoon on top of the pork. Top with the arugula.
The mustard fruit yields 4 cups. Store the leftovers in the refrigerator; it goes well with roasted meats and cheeses.