Thanks for writing. I can't think of anything you can spray in your vegetable garden that won't hurt your plants but will hurt the nutgrass.
Do you use mulch in your vegetable garden? A good 3- to 4-inch-deep layer of mulch may help to keep the pesty weed at bay --- especially if you lay cardboard or newspaper in between the mulch and the ground.
Otherwise, you can try using a non-selective herbicide such as Roundup and applying directly to the nutrgrass plants with a paintbrush. That will keep the herbicide from coming in contact with your vegetables --- but it may be time-consuming if there's a lot of nutgrass popping up.