Core cabbage. Lower into a pot of boiling water; peel off 12 leaves as they soften, about 8–10 minutes. Drain; trim thick ribs.
Heat oven to 350°F. Mix chicken, rice, onion, garlic, egg, paprika, 1/2 teaspoon salt and pepper.
Whisk tomato sauce, water, sugar, lemon juice and remaining salt. Spread 1 cup in a 9-by-13-inch dish.
Divide filling among leaves. Fold in sides and roll; place seam-side down in dish. Pour remaining sauce over rolls.
Cover tightly; bake 55–65 minutes until cabbage is tender and filling reaches 165°F. Rest 5 minutes.