Preheat the oven to 325.
Salt and pepper the pork chunks. In a heavy pot or dutch oven, heat the olive oil and brown the pork on all sides. Do it in shifts if necessary, to make sure all the pork gets browned.
Remove the pork from the oil and set it aside. Add the diced onions to the oil and cook a few minutes until soft.
Add the minced garlic, tomato paste, and red pepper flakes. Cook, stirring, a few minutes more.
Add the wine and cook, stirring constantly, until the sauce becomes thick.
Add the diced tomatoes with juice and combine with the sauce. Put the pork back in and stir so it's all coated with sauce.
Put a lid on, or cover tightly with tinfoil, and put the pot in the oven for at least two hours, until the pork is very tender and stew-like.
When the pork is done, the sauce should be thick, not liquidy. If necessary, simmer on the stovetop to cook off the excess liquid.
If the pork is very fatty, shove the pork to one side of the pot, let the fat collect on one end, and drain it out with a spoon.
Serve with parmesan mashed potatoes.