Heat 1 tablespoon of olive oil in a skillet set over medium heat. Cook the onion and garlic until softened but not browned. Let cool and transfer to a large mixing bowl. Squeeze the excess milk from the bread and add the bread to the bowl. Add the beef, egg, oregano, coriander, cumin, cinnamon, nutmeg, lemon zest, salt, and pepper. Mix by hand until smooth. Form into little meatballs, about 1 ounce each.
Heat the remaining 1/4 cup oil in a large skillet over medium heat. Dust the meatballs in flour and shallow-fry them until golden brown. Transfer to paper towels to drain.
To serve: Place on a platter and garnish with lemon wedges and torn mint leaves.