Pick the substitute based on texture: passata for smooth, crushed tomatoes for classic body, tomato sauce for convenience, pizza sauce for seasoned flavor, or paste+water for pantry-only.
Match tang: stir in a teaspoon of vinegar or lemon juice per 1 cup substitute, then taste and fine-tune salt and herbs.
If it’s watery (especially crushed/paste), simmer 3–5 minutes until glossy and spoon-coating.
Use immediately for pasta; for baking, reduce by simmering 2–3 minutes so it doesn’t leak.
Adjust thickness at the end: add a splash of water for looseness or simmer longer for a thicker marinara.