Mix all the ingredients for the meatballs. Form into balls about 2 and 1/2 inches in diameter (I had four balls).

Heat a non-stick frying pan. Cook the meatballs over medium-high heat until lightly browned. Unless your meat has too little fat, the meatballs should render enough fat to brown in. Otherwise, you may have to brown them in a little olive oil. You’re not cooking the meatballs through at this point but just browning them. As soon as they brown, scoop them out.

Heat the tomato sauce in the same pan in which the meatballs were browned. When bubbly, return the meatballs to the pan. Cook over medium-low heat, uncovered, for seven to 10 minutes, rolling them in the sauce often. The sauce should have considerably reduced and thickened by the end of the cooking time.

To serve: Place several baby arugula leaves on the bottom halves of the toasted pan de sal. Place the meatballs on top of the leaves. Spoon a little sauce over them. Sprinkle with grated cheese and finely sliced parsley.