Picadillo-stuffed Mashed Potato Balls

Papas rellenas (stuffed potato balls) is a traditional Spanish dish. Baked instead of fried, they are a healthy and delicious way to prepare a dish from the remains of mashed potatoes.
Preheat the oven to 425 degrees.Place panko in a dry skillet over medium-high heat; cook for 3 minutes or until panko is lightly browned, stirring occasionally.Put the mashed potatoes Mom prepared in a food processor; beat until smooth. Add 1/4 cup panko and 1/4 teaspoon salt to the potatoes and beat until smooth.Heat the canola oil in a medium nonstick skillet over medium-high heat. Add the garlic; cook for 30 seconds, stirring constantly. Add beef, oregano and cumin. Increase the heat to medium-high; cook for 2 minutes, stirring occasionally, to allow them to crumble. Remove from heat; add remaining 1/4 teaspoon salt, raisins, olives, and ready-made turkey gravy.Transfer the remaining 3/4 cup panko to a shallow bowl. Cover the jelly roll pan with foil and apply cooking spray. Using 3 tablespoons of the potato mixture, arrange the potato mixture around 1 tablespoon of the beef filling with a slide to form a ball. Roll in panko to coat. Place on the prepared baking sheet. Repeat with the remaining potato mixture and beef filling to make 12 balls. Brush the potato balls with cooking spray. Bake at 425 ° C for 20 minutes or until golden brown.Combine the arugula, olive oil, and juice in a large bowl; toss to coat. Serve the salad with potato balls and lemon wedges, if desired.