Existing tortilla crisp packaging.

Here are the crisp packets which compete with Doritos UK market, they sit next to Doritos on the shelves.
ALL of these packs have some Mexican theme behind them, various packs use a more traditional typeface (Phileas Fogg, Morrisons own, Casa Fiesta and Trato's). Most use related colours, bright yellow and orange for that Mexican flare and some have a washed colour to show tradition and age-old recipe.

Tesco even use a stereotypical Mexican man!

This may be a sign to avoid whats already out there but I would happily buy a pack of Tortillas assuming they had a traditional Mexican flavour by the appearance of the packet, rather than a pack of Tortillas that have no resemblence to Mexican tradition.

Further research/surveying will determine our choice of Mexican Tradition or not.