Preparation

• Prepare a medium (375°F) gas or charcoal grill fire.
• In a small bowl, combine 1-1/2 Tbs. of the fennel seeds, 1/8 tsp. of the allspice, and 1/8 tsp. each salt and pepper. Stir in the oil and then press the mixture onto the pork. Grill the pork, turning with tongs, until nicely browned on all sides and 140°F to 145°F in the center, 17 to 21 minutes. Transfer the pork to a cutting board and let rest for 5 minutes.
• Meanwhile, in a small bowl, combine the mayonnaise with the remaining 1-1/2 Tbs. crushed fennel seeds, 1/8 tsp. allspice, 1/8 tsp. salt, and several grinds of pepper. Spread the rolls with the mayonnaise mixture. Thinly slice the pork crosswise. Arrange the pork on the rolls with the cucumbers and dill. Serve warm.