In a small bowl mix the sauce ingredients together, set aside.
Heat the skillet over medium-high heat.
Cook the bacon until nearly done, about 3 minutes. (It will finish cooking in the oven.)
Remove bacon; set aside.
Add the onions to the bacon renderings and cook until they start to soften, about 3 minutes.
If there is an excess of bacon renderings, drain now.
Add pork and beans to the onion in the skillet, stir well.
Pour in the sauce mixture, stirring until it is fully incorporated.
Lay the bacon across atop of beans, some slices may need to be cut to fit any holes.
Place in oven and bake uncovered for an hour.
Remove from oven and allow to cool for a minute or two.
Serve from the skillet or transfer to a serving bowl or platter; enjoy.
Notes
Use Pork and Beans, Not Baked Beans: Canned pork and beans in tomato sauce are the right starting point. Canned "baked beans" are already seasoned and will make the final dish too sweet.
Don't Fully Cook the Bacon First: The bacon finishes cooking in the oven. If you crisp it fully on the stove top, it'll burn during the bake.
Be Gentle with the Beans: Stir carefully when mixing in the sauce so the beans stay whole.
Cast Iron is Key: A cast iron skillet gives you better heat distribution and those caramelized, slightly crispy edges where the beans meet the hot pan. That's one of the best parts.
Store Leftovers: Keep leftover baked beans in an airtight container in the refrigerator for up to 4 days. Reheat gently on the stove top or in the oven.