"All you need is lots of colorful vegetables like carrots, peppers, some onions cut small chunks, rice and salad dressing."
Could you please help me with “some onions cut small chunks”. I would like a compound noun. Is it “some small onion chunks”?
A "dice" usually refers to chopping up food into small chunks or squares. Onions are generally "chopped," although I suppose "diced" is acceptable, as well. You can have onions "chopped finely" or "chopped coarsely."
And if you wanted to go with the "chunks," which is OK, you need to say "cut INTO small chunks"
I am a cook, so I understand why you might want to say "chunks."
Stylistically, in a recipe parentheses might be helpful --
"vegetables like carrots, peppers and onions (cut into small chunks), rice and ..."
I would guess that your carrots and peppers should also be in small
chunks. In this case, you would write "(all cut into small chunks)".