Get a large pot on the stove, pour in olive oil and turn flame to medium-high. Add in the minced onions once oil is hot. Cook for 5 minutes until they start to brown. Clean the artichokes with warm water, cut off the stems and pointy tips of the leaves with scissors.
Add in the sliced garlic and chili flakes, cook for a couple minutes.
Add in the sugar and vinegar and cook down for a minute. Add the artichokes to pot and cover with the crushed tomatoes and water. Make sure that the artichokes are almost covered with the liquids to ensure even cooking.
Bring the pot up to a boil and then turn down to a slow slimmer and cover with the lid. Cook for 3-4 hours depending on how large the artichokes are. Test the artichokes by pulling off an outer leaf and eating the end to see how tender it is.