Shuck fresh corn on the cob removing as much of the silk as possible.
Brush with olive oil and season with salt.
Grill over high heat until the corn is golden and a little charred all over.
Remove the corn from the heat and allow to cool for 10 minutes.
Slice the corn kernels off the cobs and place in a large bowl.
Make the dressing: Combine the avocado, chopped jalapeño, fresh herbs, lime juice, water, olive oil, salt and pepper in a food processor or blender then blend until smooth.
Taste and adjust seasoning if necessary.
Assemble: Add cubed avocado and crumbled feta to the corn then pour over the dressing.
Toss and transfer to a serving bowl, top with fresh cilantro/coriander and finely chopped chillies (optional).