To make the sauce, place all of the ingredients into a small pot over a low heat and gently cook for 15-20 minutes, ensuring it does not boil. Cool to room temperature then pour into a small food processor or blender and blend until smooth. This can be made up to week in advance and stored in an airtight container.
Drizzle a little oil over bug meat and with salt and pepper. Grill on each side for 1-2 minutes until just cooked through. Remove from the sprinkle over the zest of the lime.
Warm the street tacos in a dry pan over a medium heat for one minute on each side until soft. Keep warm in a clean tea towel.
To serve, portion lettuce between each taco then place bug meat on top. Squeeze over lime juice and then drizzle over chilli sauce. Garnish with coriander.
