Heat a generous splash of olive oil in a frying pan over medium-high heat and cook the garlic and shallot for 2 to 3 minutes, until soft. Add the anchovy fillets and let them “melt” while stirring continuously, about 2 minutes.
Add the tomatoes and vinegar and let the mixture simmer for 3 to 4 minutes with a lid on, then crush with a potato masher.