Since I have done a Whole30 before, I get this question pretty frequently. You'll have to be very careful with your ingredients, and of course you won't be able to add any sweetener unless you use soaked and blended dates, so sweet and sour sloppy joes are out for the duration of your whole30. But, if you serve them as lettuce wraps or over sweet potatoes or russet potatoes, you can certainly make a Whole30 compliant sloppy joe mix with ground beef, Whole30-approved Ketchup like Tessemae's or canned whole tomatoes, mustard, chopped onion, green or red bell pepper and garlic, a touch of vinegar. I found this recipe for Whole30 Sloppy Joe Bowls for you that you might really enjoy--it sounds good to me!