Decide how you used jerusalem artichokes (roasted/sautéed vs mashed/puréed vs baking thickener) and pick the closest match from the table.
Use the listed substitution ratio; for drier options (like parsnip/rutabaga), lean toward the higher end and roast until tender.
If your substitute is less sweet than jerusalem artichoke, add a small boost (honey or a pinch of sugar) and re-taste after cooking.
If your substitute is less starchy, increase cooking time slightly or mash/purée more thoroughly to get the same body.
Finish with the same seasoning style you’d use for jerusalem artichokes (butter/olive oil, salt, pepper, and a nutty note like toasted garlic or nutmeg).