Can I use this walnut oil for cooking, and if so, what's the best way?

You can use this oil in meal preparation, but the method matters to get the best from it. Because it is an unrefined, cold-pressed oil, its delicate aromatic compounds and characteristic taste are preserved by avoiding strong heat. For this reason, it is less suitable for high-heat frying, searing, or deep-frying, as such temperatures can degrade the flavor and potentially create bitterness.

The best culinary uses are applications where heat is minimal or applied after cooking. You can gently warm it in a pan for a light sauté at low temperatures. More traditionally, it excels as a finishing oil: drizzle it over already-cooked roasted vegetables, pasta, or soups; whisk it into vinaigrettes and cold dips; or add a spoonful to porridge or soft cheeses. This approach allows the deep, slightly sweet nutty taste to shine without being compromised. For high-heat cooking, a more neutral, refined oil would be a better choice.