Persian leek (tareh)
A Persian leek with narrow, flat leaves that is used like a herb. It tastes mildly of onion, somewhere between chives and leek.
Tareh is an Iranian form of leek grown only for its long, narrow, flat leaves. It does not form a thick shaft like a European leek. The flavour is mildly oniony and grassy, stronger than chives but finer and less sweet than leek. The leaves are tender enough to be eaten raw or finely chopped and cooked in large quantities, and they belong to many Persian herb mixtures. Fresh tareh is found almost only in Iranian or Afghan grocery shops, often also frozen or dried, occasionally in well-stocked Turkish supermarkets or by mail order.
Substitute:
A mix of chives with the tender greens of spring onions or young leeks comes fairly close in flavour; garlic chives also work but add more garlicky sharpness. Leek greens alone are tougher and sweeter and should be sliced very finely.