Your support team member could either get you food from a restaurant or give you food that they made without you present. Or if you need to start even smaller, you could watch them make your meal so you know it's safe. Eat with them. Notice your feelings. Use anxiety reduction and grounding techniques. Keep breathing and do your best. Keep practicing this step until your anxiety stays below a 7 on a 0-10 scale with 10 being the worst anxiety you've felt and 0 being no anxiety at all.
Increase the challenge slowly
Once you get comfortable with eating meals made by others, up the ante. If you're still not ready for restaurant dining, try getting take-out or try eating foods you didn't see being prepared. Use an affirmation like "This food is safe and nourishing; I am safe and I can eat this food". Make sure you start off each experience with some breathing and relaxing techniques so that you don't associate fear with the experience.
Dining Out
If noise bothers you, choose a restaurant that's quieter or a time of day that's less intense like lunch. See if you can get a table that's against a wall, in a corner or in a quieter area of the restaurant. This reduces over-stimulation and feelings of vulnerability.
Have a plan
In earlier recovery, it's helpful to have a plan. If you know which restaurant you'll be going to, look up their menu online. Work with your therapist or dietician to determine which menu item you'll be selecting. Most restaurants have portions that are significantly larger than the exchanges on your meal plan. If this is the case, you could anticipate eating half the meal. One tip is to ask for a to-go box at the beginning of the meal so that you can put half away for later and just focus on what's on your plate.