Sprinkle the pork with salt and transfer to a bowl. In another bowl, combine the chopped olive oil, oregano, garlic, shallots, jalapeno, lemon zest and juice. Stir to combine, and then pour half of the marinade over the pork. Massage to coat, cover with plastic wrap and refrigerate at least 3 hours or overnight.
Remove the pork from the refrigerator to take the chill off. Soak the wooden skewers in salted water at least 20 minutes. Tie the remaining oregano into a bundle to make a basting brush, and dip in the reserved marinade.
Preheat a grill or grill pan to medium.
Remove the pork from the marinade and thread 2 pieces onto each skewer. Grill until lightly charred, about 1 minute, and then brush with the marinade and flip. Baste again, and grill for 1 minute on the second side.
Transfer the skewers to a sheet of foil. Pour the remaining marinade over the meat, add the oregano bundle and crimp the edges of the foil together to make a sealed package. Place the foil package on the grill until the meat is cooked through, 3 to 5 minutes longer. Grill the fruit cut-side down until lightly charred, about 1 minute.
Serve the souvlaki with the grilled citrus squeezed over or on the side.
Per serving (based on 6 servings): Calories 278; Total Fat 13 grams; Saturated Fat 2 grams; Protein 32 grams; Total Carbohydrate 8 grams; Sugar: 5 grams; Fiber 1.5 grams; Cholesterol 98 milligrams; Sodium 178 milligrams;