For the dressing, in a small bowl, combine dijon mustard, apple cider vinegar, olive oil, honey, garlic, lemon juice, salt and pepper. Whisk with a fork until well emulsified.
For the salad, heat butter in a grill pan on medium high heat. Once hot, sear the corn on all sides until slightly charred and tender. Remove from the skillet, cool, then cut the corn off the cobs. To a medium bowl, add the tomatoes, corn, cucumber, red onion and fresh basil.
Once combined well, pour the dressing on top and stir until coated well.
Refrigerate until ready to serve.