Heat the vegetable oil in a small saucepan over medium-low heat.
Add the dried chili flakes, minced garlic, chopped onion, and shallot to the saucepan. Stir well to combine.
Cook the mixture for about 5 minutes, or until the onions and shallots have softened and become translucent.
Add the sesame seeds to the saucepan and continue cooking for another 2 minutes, stirring occasionally.
Stir in the salt and sugar, and cook for an additional minute to dissolve the sugar.
Remove the saucepan from heat and let the chili crunch oil cool down completely.
Once cooled, transfer the chili crunch oil to a clean jar or airtight container.
Store in the refrigerator for up to 2 weeks.