Once water is boiling, add in your corn cobs and let them boil for 10 minutes.
While your corn is cooking, cut up your tomatoes and avocado into bite-sized pieces. Dice your cilantro and red onion and add all into a medium-sized salad bowl.
Drain using a strainer or use tongs to remove the corn. Be careful not to get burnt with the boiling water.
Run corn under cold water to cool off completely.
Slice down the sides of corn of the cob to remove the corn kernels. Put corn into the salad bowl.
To make the dressing, whisk the oil, lime juice, cumin, minced garlic, salt and pepper in a small bowl.
Drizzle dressing over salad and mix well.
Serve or store in the fridge for one day. If you want to save longer (3 days), keep out the avocados until ready to eat.