Since Dinah canonically has a big appetite and loves to eat and Barry is a chronic OCD overthinker who stresses over perfect social interactions my ideal friendship between them starts with Dinah noticing that for a guy who needs to eat a lot he sure is reluctant to actually eat in anyone's company, especially outside of their hero identities. And of course, being a great detective herself, it doesn't take her long to find out how anxious he gets over portion sizes and appearing 'impolite' or 'messy'
So anyway this is how Dinah starts dragging him out to eat with her and sitting with him in the JL cafeteria because she also eats a lot of food and is loud and messy and slurps her food and burps without restraint so Barry can freely enjoy his own meals because nobody will be looking at him anyway when she's taking up all that space
Which is then how Barry starts repaying her by just whizzing her over to whatever new food place she's heard about around the globe that she wants to try. And then they bond over their mutual dislike for computers and other modern technologies lol
