Decide what you need from apple cider: fruity sweetness, tang, or both (use “+ lemon” for brightness or “+ vinegar” for acidity).
Start with the 1:1 ratio for most swaps, then adjust by taste: add a splash more acid for sharpness or reduce gently for sweetness.
If substituting for baking, stir the swap into wet ingredients and rest batter 2–3 minutes so flavors meld.
If substituting for simmered sauces, heat the swap 3–6 minutes to thicken slightly and round the flavor.
Taste at the 1st pour and again after a short heat step; cider varies by brand, so micro-adjust with lemon or vinegar.