If I was in a position to implement it, I think I would like to introduce a 'food sourcing' document, that has to be signed off and retained at all stages of the supply chain, and giving powers to health inspectors to spot check, verify, seize, and impose hefty penalties if certification cannot be produced or verified (ie the sourced foods do not match what the document says.

This would mean that ingredients could only be purchased from suppliers that meet health and safety standards - so for example, if horse meat is used, each step in the chain may be asked to prove that they have purchased this from a reputable source, and not drug/disease ridden.