Heat a grill pan over a high heat.
Brush corn and spring onions with oil and season with salt.
Arrange in the grill pan and char all over. The spring onions will take half the time of the corn to char.
Cool enough to handle and rough chop the spring onions and slice the kernels from the corn.
For the dressing, whisk all of the ingredients together.
In a large salad bowl, combine the lettuce, avocado, fetta, freshly torn herbs, drained tuna, corn and spring onions.
Just before serving, drizzle over the creamy dressing and toss everything together.
Serve with extra basil and dressing on top.
