Cooking the veggies in bacon fat adds smoky flavor to this comforting soup. Slideshow: More Warming Soup Recipes
In a large heavy pot, cook the bacon over medium heat, turning occasionally, until crisp, about 8 minutes. Transfer the bacon to paper towels to drain, keep the fat in the pot.
Stir the onions, garlic, and 1/2 teaspoon each salt and pepper into the fat in the pot and cook, stirring occasionally, until golden, 8 to 10 minutes. Stir in the carrots, celery, stock, and split peas and bring to a simmer. Cook, stirring occasionally, until the split peas are very soft and falling apart, about 1 1/2 hours. Season the soup with salt and pepper to taste and crumble the reserved bacon over top.