Plat principal vs. plat de résistance

In French cuisine, the terms 'plat principal' and 'plat de résistance' both refer to the main course of a meal, where the heaviest, most substantial dish is served. However, 'plat principal' is more commonly used nowadays, while 'plat de résistance' has an older connotation and is less frequently used.

Plat principal

Literally translates to 'main dish', this is the term widely used today in French-speaking countries to denote the central part of a meal.
Pour le dîner, le plat principal sera un filet mignon accompagné de légumes sautés.
(For dinner, the main course will be a filet mignon with sautéed vegetables.)
En plat principal, je choisis souvent du poisson pour rester léger.
(As a main course, I often choose fish to keep it light.)
Dans ce restaurant, le plat principal est servi avec une salade et des frites.
(In this restaurant, the main course is served with a salad and fries.)

Plat de résistance

This phrase also means 'main course' but carries an old-fashioned ring. It implies a substantial or 'hearty' dish that can stand up as the centerpiece to a meal.
Le plat de résistance d'aujourd'hui est un boeuf bourguignon traditionnel.
(Today's main course is a traditional beef bourguignon.)
Autrefois, le plat de résistance était systématiquement une viande lourde ou un ragoût épicé.
(In the past, the main course was invariably a heavy meat or spicy stew.)
A l'époque, on attendait avec impatience le plat de résistance lors des grands banquets.
(Back then, people eagerly awaited the main course during large banquets.)

Summary

'Plat principal' and 'plat de résistance' are French terms used to describe the main course of a meal. While their meanings are similar, 'plat principal' is more common in modern usage and tends to reflect a broader variety of dishes. In contrast, 'plat de résistance' has historical roots and often referred to heartier fare. With changing culinary trends and terms, 'plat principal' has become the preferred choice in contemporary French language.