Learn Spanish (Latin America): El guiso es tan picante como para enmascarar el sabor del pollo. - The stew is so spicy as to mask the flavor of the chicken.

We use the infinitive here because there is no subject change. The stew (el guiso) is the thing that is spicy, and the stew is also the thing doing the masking. If a different subject were introduced (for example, "so spicy that I couldn't eat it"), you would need como para que followed by the subjunctive.

How exactly does the phrase tan picante como para enmascarar work together?

This structure sets a "threshold of degree." It means the stew has reached a high enough level of spiciness (tan picante) that it triggers the result of hiding the chicken's flavor (como para enmascarar). In English, it translates literally to "so spicy as to mask," but you will also often translate it simply as "so spicy that it masks."

Could I say El guiso está tan picante instead of es tan picante?

Yes, and it changes the nuance slightly. Using es implies that being this spicy is a defining characteristic of this particular stew (perhaps that is just how the recipe is made). If you use está, you are reacting to how it tastes right now, perhaps implying it turned out spicier than usual. Both are perfectly natural here.

Is enmascarar the best verb to use when talking about overpowering flavors?