This instruction in Genesis 1 is almost unique in the Old Testament. It has a counterpart in Genesis 9:3, where meat is now expressly given to Noah and his descendants. However, the only other place in the Old Testament where a vegetarian diet is represented as superior to eating meat, is in Daniel 1:3-15. This is no surprise if you understand (as I do), that Genesis 1-11 were written in Babylon during the exile, most likely by Daniel himself. This makes a lot more sense of the instruction in Genesis 1; it’s part of Daniel’s anti-pagan polemic.