Step 1

Heat a small saucepan over medium-high heat and add the oil, onions, shallots, and a heavy pinch of salt, and toss to coat with the oil.

Step 2

Reduce the heat to low and allow the onions and shallots to soften, then caramelize for about 15 minutes, stirring often.

Step 3

Stir in brown sugar, then the tomatoes, followed by the tomato paste and vinegar. Simmer until the mixture is thick and bubbly.

Step 4

Stir in the broth and reduce to a jam-like consistency over medium-low heat.

Step 5

Remove from heat and set half the mixture aside. Puree the other half and fold it back into the reserved mixture.

Step 6

Fold in the basil and allow to sit at room temperature for 15 minutes.

Step 7

Taste and adjust seasoning with salt and black pepper, if desired.