Heat 1 tablespoon olive oil in a skillet over medium heat; cook and stir onion and garlic in the hot oil until garlic is fragrant, 2 to 3 minutes. Add kale, salt, and pepper; cook, stirring occasionally, until kale is wilted, about 5 minutes. Stir tomato and carrots into kale mixture; cook for 5 more minutes. Remove skillet from heat.