Yes, we know what you're thinking. But we promise, this is absolutely delicious. Let's call it "ethical foie gras" - the sort made with some of the most nutritious foods on the planet - infused with garlic, lemon, and love.
In a small pan, heat olive oil and saute minced shallot and garlic until softened and beginning to brown. Remove from heat.
Drain the can of cod liver, reserving the oil.
Add the sardines, drained cod liver, lemon juice/zest, fish sauce, shallots/garlic, and egg yolk to a food processor and process until smooth.
While the processor is running, slowly drizzle in the reserved cod liver oil in a steady stream until incorporated (as if you were making mayonnaise). The final consistency should be very soft and creamy.
Serve immediately. This will keep about 2 days in the fridge.