I see no visible effect from Zheng He's voyages at all. There was regular trade with China's neighbours, both by land and sea - even with no great voyages of Zheng He, there was cultural exchange. The seaborne trade did influence Chinese cuisine a lot, but the largest impacts were well after Zheng He - specifically, the introduction of a number of New World food plants, mostly through the regular trade with Manila. The actual routes for the introduction of these plants are, in many cases, not reliably known (and perhaps genetic analysis could shed some light on these). As well as the trade with Manila (connected by the Spanish to Mexico), there was trade with India and other parts of SE Asia, such as Batavia, by which New World plants could be introduced, and direct trade with Europeans.

The most important new crops that were introduced were

• peanuts, which rapidly became a major oilseed crop,

• maize and the sweet potato, which proved important as famine foods and allowed populations in regions unsuitable for rice production to increase greatly (the potato (the "Irish potato") had an even bigger impact on Tibet when it was introduced), and

• chillies.

All of these were introduced to Japan, possibly via China (or Korea). Maize had relatively little impact in Japan until modern times, as stock feed, but the others were integrated into Japanese cuisine, and sweet potatoes became an important crop.

As for curry, curry had limited diffusion into Chinese cuisine. There are old curry traditions in SE Asia, from Indianisation of the region, which long predates Zheng He. These curries made their way into Chinese communities in SE Asia, and appear to have travelled back to China through family connections (and this might be a quite recent diffusion). There are also curries in Yunnan (e.g., Thai nam ngiao) that are basically cross-border Burmese or Thai dishes.

Compared with these impacts on Chinese cuisine, and the exchange of food and cooking with Central Asia by land, any impact of Zheng He on Chinese cuisine is vanishingly small - invisible, if not zero.

Japanese curry had an entirely different (and recent) route, being adopted from the English in the late 19th century as a Western dish that could be eaten with rice, for military cooking. I discussed this in more detail in https://www.reddit.com/r/AskHistorians/comments/b223ix/how_and_when_did_curry_become_a_part_of_japanese/