Issue asset in the transaction
I want to issue assets in some transaction,
Buyer A, Seller B
B sell an asset (call "beef") to A, but B don't have "goods" in chain.(but B have "beef" in real world)
A want to buy this "goods" from B by an asset (call "pork"), but A also don't have any "pork" in chain. (but A have "pork" in real world)
So A and B exchange "pork" and "beef" in realworld, and they issue "pork" and "beef" in chain to exchange.
How can I do that?
I know that is risk for the blockchain, but this is my academic testing.