Cut cherry tomatoes in half and sprinkle with salt. Set aside for 25-30 minutes and drain excess juice from the tomatoes.
Brush 3 tbsp olive oil on corn ears, and sprinkle corn with chopped cilantro and cumin seeds. Coat ears evenly with cilantro and cumin.
Heat cast iron skillet over medium high heat and add corn ears. Roast corn for 12-15 minutes or until corn is slightly charred. Rotate the ears with a tong every few minutes to prevent from burning and reduce heat to medium if corn is charring too much. Add extra olive oil to the corn if necessary. When done, take corn ears out of skillet and set aside to cool.
Add 2 tbsp olive oil to the same skillet and sauté red onions over medium heat until tender. Turn off heat and let onions cool.
Once corn is cooled, cut corn off of cob using a knife or a corn stripper and transfer to a bowl. Toss in sautéed onions, cherry tomatoes, hatch chiles to the bowl. Finish off by adding fresh lime juice, salt and fresh ground pepper. To serve, garnish with fresh cilantro leaves.