What is the best way to find a cofounder?

I would strongly suggest not to start with Friends as a co-founder. The vision and fire which you have for the idea may not be the same case for your friend. His priorities can be different... But like in friendship it happens ki ha bhai ti shuru kar ham tere saath hain...This is totally a shitty situation. They will have next to no contribution and you will have all the pressure. Better to find people based on skills which are totally opposite to you that way you can find a co-founder and some level of discipline and professionalism is also maintained.

Ask if they have their passport with them :)

Acquaintances/friends and family is a good place to start. Going through platforms events etc is a big risk.