Not an onion but a smaller yellow squash which can definitely be mistaken for a large onion.

I play this only when required by the task list and then I bomb more than I win. The difficulty is the time pressure to figure out logically where the bombs are likely to be. A cheat to help relieve the time pressure while calculating is to screen print the step you're at and pause the game while you study the image, then go back and pick only the ones you decide are safe, then repeat the process. It improves your chances of winning but the risk is that the game may shut down requiring you to reboot the game if you take too long. The bright side of this is that you won't lose any energy points if you need to reboot midgame, but you'll have to start anew.