What is a vegetable stalk with tart flavor?

There are a few possibilities here, depending on what you mean by "stalk" and "tart flavor". Here are a few contenders:

* Rhubarb: Rhubarb is a vegetable with stalks that are famously tart. They are often used in pies, jams, and other desserts.

* Asparagus: Asparagus stalks can have a slightly tart flavor, especially if they are cooked for a long time.

* Celery: Celery stalks can also have a hint of tartness, especially if they are very fresh.

If you're looking for a more specific answer, could you tell me:

* What type of vegetable are you thinking of?

* How tart is the flavor you're looking for?

This would help me give you a more accurate answer.