Place the whole habanero peppers and unpeeled garlic cloves on a baking tray lined with foil.
Place under a medium-high grill and cook for 8-10 minutes, turning every 2-3 minutes, until the habaneros are charred and blistered in places and the garlic is soft. The habaneros should be just starting to blacken — this char is what gives the salsa its distinctive smoky depth.
Remove from the grill and allow to cool for 5 minutes until comfortable to handle.
Wearing gloves, remove and discard the habanero stems. Deseed the habaneros if you want to reduce the heat slightly — for maximum heat leave the seeds in.
Squeeze the garlic cloves from their skins — they should pop out easily.
Place the charred habaneros and garlic in a pestle and mortar or food processor along with the salt. Grind or blend to a rough paste — leave some texture rather than blending completely smooth.
Add the lime juice, orange juice and lime zest if using. Mix well. Taste and adjust salt.
Transfer to a sterilised jar or bottle. Store in the fridge for up to two weeks.
