Heat oil and one and a half tablespoons margarine in a saucepan over medium heat. Cook onion and garlic until soft, then add rice and stir for two to three minutes. Add 1/2 cup stock and stir until the liquid is absorbed.

Continue adding stock, half a cup at a time, for 20 minutes, until rice is tender yet firm. Remove from heat. Stir in remaining one and a half tablespoons margarine and salt and pepper to taste. Spread the risotto onto a tray and refrigerate to chill completely.

To make tomato relish, heat olive oil in a frying pan over medium-high heat. Add onion and garlic and cook for three minutes or until browned. Add tomatoes and stir for five minutes or until soft. Add tomato paste and stir for two minutes or until thick and cooked through.

Prepare a dredging station for arancini with flour in one shallow bowl or plate, beaten eggs in the second, and breadcrumbs in the third. To form arancini, use wet hands to shape the risotto into a ball. Press your thumb into the center of the ball to make an indent. Place a teaspoon of bolognese sauce into the indent, then mold risotto around the sauce to enclose.

Roll in flour and shake off excess. Dip in egg, then in breadcrumbs, pressing to coat. Refrigerate for 30 minutes.

Preheat oil in a deep skillet until it reaches 340 degrees Fahrenheit. Fry arancini until golden brown, then transfer to a paper towel-lined plate to remove excess oil.

Gently warm the tomato relish and place a large spoonful in the middle of each deep plate. Place arancini over relish and top with a dollop of mayonnaise. Garnish with cilantro.