Go for a hike in the countryside in many parts of Greece, and you'll smell it: fragrant wild oregano, its flowering shrubs growing in valleys and on hillsides. Rigani, as it is called in Greek, is arguably the most important herb in the country's cooking, providing a signature flavor for countless dishes. Almost always used in its dried form, it is crumbled over foods as a finishing touch or added to both fresh and cooked preparations to lend savory depth.
Origanum vulgare hirtum, the subspecies that's native to Greece and Turkey, is the one most prized by Greek cooks because of its high concentration of aromatic compounds, which make the herb extraordinarily spicy and pungent. I've seen cooks use it to season every kind of dish, from hearty, feta-studded salads to vegetable stews. They sprinkle oregano over grilled fish and egg dishes, and they blend it with oil and lemon juice to make marinades for meat, especially for souvlaki. The herb's palate-awakening bite seasons all sorts of meze, including keftedes (meatballs) and shrimp saganaki baked with tomatoes and feta, and it's even brewed into tea.