In a large skillet cook bacon over medium heat until crisp. Remove bacon and drain on paper towels, reserving 1 tablespoon drippings. Crumble bacon; set aside.
In a large bowl combine the reserved drippings, mayonnaise, vinegar, sugar, and celery seeds. Add cabbage, carrots, sunflower kernels, tomatoes, and green onions; toss gently to coat. Stir in crumbled bacon. Season to taste with salt and pepper. Transfer coleslaw to a bowl or storage container; cover and chill overnight.
Serve within 2 hours after removing coleslaw from refrigerator; discard any leftovers.