Leustean (EN: 'Lovage') is pretty much the most savoury plant on earth. It lacks the pungency of basil, but it is no less aromatic. It's not as sharp on the nose as mint is, nor as fragrant as thyme, nor as earthy as oregano or parsley. While the comparison to celery is not completely out of order, it's still like comparing rucola to leaf lettuce.
An added bonus is the plant's versatility; you'll find that it works in pretty much any hearty comfort food. I've recently used it in a peperonata and it was a clear upgrade from the usual parsley. Like Sriracha, you could basically put it on a piece of cardboard and it'll be tasty. Finally, it stores beautifully. Roll it in shrink wrap and freeze it as long as you want. It's just as good when you take it out.
Like many other great things about Romania (or living in Romania), the plant is underrated and/or under-appreciated. But any Romanian tanti worth her salt has an endless supply on hand and wouldn't dream of serving a hearty soup without a healthy sprinkling of leustean. What I don't understand though, is why this is far less common in the restaurants here. It's as if they're afraid that any dish using it will taste too much like dinner at grandma's. Ironic when you consider the typical appeal to tradition that Romanian restaurants
If you're hoping to hit Flavour Town, Romania, the lovage flavour train will get you there, just head to the local piata and hop on.