Begin by opening a can of sardine fillets packed in olive oil. Drain the excess oil into a bowl, and place the drained sardines in a food processor.

Dice half of a medium onion and chop a handful of fresh parsley. Set these ingredients aside for blending.

In the food processor, combine the drained sardines, 4 ounces of unsalted butter, chopped onion, parsley, and the juice of half a lemon. Optionally, add tomato paste.

Pulse the mixture until roughly combined, about 20-30 seconds. Add reserved olive oil if the mixture is too thick, blending until smooth.

Taste the sardine pâté and season with salt and pepper to your liking. Blend again briefly to incorporate.

Transfer the pâté into a serving bowl and let sit at room temperature for 10-15 minutes before serving with toasted baguette slices or crackers.