The UK chocolatier Divine Chocolate Ltd. uses Fair Trade chocolate from a cooperative of cacao farmers in Ghana, called Kuapa Kokoo. Unlike the straight chocolate bar, this one is flavoured with mint, both as a peppermint crisp (mint-sugar) and as a peppermint oil. The cacao content is at 70% and the ingredient listing looks good, cocoa mass, sugar, cocoa butter, peppermint crisp (5% - sugar and peppermint oil) soya lecithin, peppermint oil and vanilla (all but the peppermint oil Fair Trade).
How did it taste? The mint flavour is definitely there, and it pairs well with the dark chocolate, and I liked the pairing of the two flavours, but I found the peppermint crisp disconcerting (it felt like I was eating crunchy sugar bits - which is what it is, but I don't think it's really needed - just the peppermint oil is good enough). This was bought at a health food store for about $3. I don't know if I would buy this bar again.