Diners in China turned to ready-made dishes for their annual reunion dinners on the eve of Monday’s Lunar New Year holiday, as busy schedules and new offerings from restaurants and supermarkets prompt a shift in traditions.

The reunion is customary for many Chinese-speaking communities around the world. Families traditionally get together for a freshly prepared feast to mark the end of a year and welcome another.

But in China ready-made dishes or meals, which are pre-prepared and can be warmed up in a few minutes, are coming into fashion, as time-starved urbanites seek quick solutions. Shortcuts are especially welcome for complicated traditional dishes such as braised dongpo pork elbow or Buddha jumps over the wall, a meat and seafood stew that can require up to 30 ingredients...