Heat a large frying pan over medium heat, add 2 tbsp oil, half the onion and half the garlic, and stir occasionally until soft (7-10 minutes). Cool completely.
Combine minces, pecorino, herbs, breadcrumbs, egg and onion mixture in a large bowl, mix well and season to taste. To test seasoning, heat a small frying pan over medium heat, add ½ tsp oil and 1 tbsp mince mixture and cook through, turning once (1-2 minutes). Check seasoning, adjusting mince mixture to taste. Roll mixture into walnut-sized balls, place on a baking paper-lined tray, cover and refrigerate until firm (1 hour).
Heat 1 tbsp oil in a large frying pan over medium heat, add one-third of the meatballs and turn occasionally, until golden and cooked through (5-7 minutes). Remove, set aside and keep warm. Wipe frying pan with absorbent paper and repeat with remaining polpette.
Return pan to heat, add remaining olive oil, onion and garlic and stir occasionally until soft and translucent (5-7 minutes). Add wine, reduce by half (2-3 minutes), add tomato and stir occasionally until starting to thicken(3-5 minutes). Return polpette to pan, stir to coat with sauce, remove from heat and season to taste.
To serve, halve rolls, divide polpette and sauce among bases, top with provolone and rocket, season to taste, sandwich with tops and serve immediately.