The most renowned global cuisine can't gain mainstream traction in America

Something is missing in the US fast-casual sector.

Flashy and aromatic flavors found in Mexican food and Asian cuisine are proving immensely popular.

Even more adventurous fare like Middle Eastern or African food are on the rise.

But of all the varied and respected global cuisines, there is one glaring omission from the US restaurant market: French food, according to Nation's Restaurant News.

French cooking is renowned the world over - it's virtually synonymous with the idea of fine eating.

And while there's certainly a strong market for upscale French restaurants, there's a noticeable lack of fast-casual chains focusing on the courtly continental cuisine.

Why is this? What's the French connection?

There are a few reasons. Current restaurant trends lean towards the bright and exotic "ethnic" flavors of South American and Asian cuisine, driven by millennials' ongoing quest for spicy and authentic foods. Typically, the flavors of these cultures are quickly prepared and instantly recognizable.

French food, conversely, is a tradition best enjoyed slowly. The tastes are mellow, rich, and luxuriant - best savored languidly and cozied up to over time. Bouillabaisse and duck confit are meals that require time and attention that can't be properly served or enjoyed in a fast-casual setting.

Nor is a steaming plate of escargot the most practical choice for those looking for a quick and filling bite - a burrito is a much more viable option. Grab-and-go has become the norm in casual American dining.

Of course, there are a handful of exceptions. The cafe chain Au Bon Pain has met with national success - yet the menu is more broadly based in light American fare than anything truly French.

And Southern chain La Madeleine has made headway, expanding to 75 locations in eight states and Washington, DC. But its service model is cafeteria-style and focuses more on dining in, and the menu is something of a French and Southern hybrid - no snails here.

Also of note is that French cuisine, for all its oddities like frog legs and beef tongue, is not as exotic here as one may imagine.

French culinary customs are forever intertwined with American food, from steak sauces to apple pie, according to Bret Thorn of the Nation's Restaurant News. One can't run a kitchen without bumping into something lifted from the gastronomy of Gaul.

So for now, France's culinary appeal in the US remains decidedly high-end. After all, one can't expect fast-casual foie gras for the price of french fries.