Make roasted tomato sauce. Place ingredients in a 4 litre (16-cup) rectangular 23cm x 32cm cast iron roasting pan; season. Roast for 1 hour or until tomatoes soften.
Meanwhile, for sage involtini, working in two batches, place two long pieces of plastic wrap on a work surface, then place another piece on top to create a double layer. Lay 6 pieces of veal 5cm apart. Cover with another double layer of plastic wrap. Use a kitchen mallet or rolling pin to flatten veal to 5mm thick. Season.
Place 2 sage leaves, 2 slices of salami, side by side, 2 slices of cheese, side by side, about 1 tablespoon sauerkraut and 3-4 capsicum strips on each piece of veal crossways, across one short side. Roll veal up tightly to enclose filling; secure with toothpicks.
Heat half the oil in a large non-stick frying pan over high heat. Cook half the veal rolls, turning, for 3 minutes or until browned all over. Transfer to a plate. Repeat with remaining oil and veal rolls; wipe pan clean with paper towel between batches, if necessary. Add remaining sage leaves to pan; cook for 30 seconds or until crisp. Transfer to paper towel; drain.
Add involtini rolls and any juices to roasted tomato sauce in dish; top with crisp sage leaves. Return to oven; bake for 30 minutes or until involtini are tender; a small sharp knife should insert easily with little resistance.
Remove and discard toothpicks from involtini. Serve half the involtini stew. Transfer remaining involtini stew to an airtight container; cool, then store.
Roasted tomato sauce
Serve topped with lemon pangrattato and, if you like, with crusty bread and simple green salad. Refrigerate involtini stew in an airtight container for up to 2 days. Freeze for up to 3 months; thaw in the fridge, then reheat in a microwave.