Pre-heat oven to 350°F.
Over medium high heat, add the olive oil to the bottom of a heavy bottom Dutch oven.
Add the onions and garlic and cook until soft and partly caramelized.
Remove from pot and set aside.
You may or may not need to add another tbsp. olive oil at this point.
Add the pork to the heated pan, season with salt and pepper and cook for about 5 minutes, tossing often until the pork has well browned.
To the hot pot, add the celery and caramelized onions and garlic.
Add the sage and thyme, plus 2 cups of the pork stock; the stock should be boiling hot to speed up the cooking time of this recipe.
Stir together, cover and place in oven for about an hour.
Remove from oven, taste the broth and add more salt and pepper as needed.
After the hour, add the carrots with the remaining 3 cups of hot stock.
Return to the oven for 20 minutes.
Remove from oven and add potatoes.
Return to oven for another 20 - 30 minutes until the potatoes are fork tender.
Move the stew to the stove top and bring to a gentle boil over medium heat.
Slowly add a thickening slurry made by whisking together the flour and water until no lumps are left.
Stir constantly as you add the slurry to stew to avoid lumps.
Simmer for a minute or two and serve.