Cook bacon in a large skillet over medium high heat until crisp. Remove using a slotted spoon and crumble. Reserve drippings in pan.
To the drippings add the diced onion. Cook over medium-high heat for 2-3 minutes until softened and beginning to brown. Add the flour cooking over medium just until absorbed.
To the skillet add the chicken stock, diced tomatoes, tomato sauce, salt, black pepper and granulated garlic. Mix to combine.
Simmer uncovered over medium-low heat for 10-15 minutes to reduce and thicken. Stir periodically to prevent sticking.
Serve immediately drizzled over biscuits, grits, rice or mashed potatoes garnished with chives. (You can also serve it as a condiment over meatloaf, chicken, pork chops or shrimp.)
Notes
You can use butter in place of bacon drippings.
You can thicken the gravy further at the end of cooking, if needed. Dissolve 1 Tbsp of flour in chicken stock or water and whisk into the tomatoes. Simmer on medium-low heat and repeat the process until it's thickened to your taste.
Likewise, you can thin adding more stock.
Depending on how you plan on serving tomato gravy, you can crumble the cooked bacon on top or serve it on the side.
You can add a small amount of sugar to balance the acidity of the tomatoes, if needed.