An underwater-style dinner allowed Long Yi to witness what is called creativity.
There are no flames under the sea, so there is no roasted food, but there are boiled and fried dishes. These foods, due to lesser contact with air, don't oxidize due to the air. After cooking, they have a subtle difference from the food on the land. Furthermore, the ingredients and seasonings from the sea floor completely differ from those above ground – to put it simply, all of them carry a hint of fishiness. However, this fishiness doesn't deter one, instead, it stimulated the appetite.
However, that's not the point.
The real issue is how to eat in seawater.
The mermaids are all able to use a natural magic to extract freshwater to prevent the food from tasting like seawater. Long Yi, on the other hand, could only use the blessings of the water spirits to barely achieve this.