The texture of the vegetable mixture was too lumpy for my tast.

what's the texture of vegetable??

The description does not refer to the texture of a vegetable but of a vegetable mixture. For example if the vegetables are processed to form a soup or a paste.

Texture means the quality of something decided by touch. So velvet has a soft, smooth texture. In this case the vegetable mixture is too lumpy for the writers taste.
thank you so much ;-)