Rillette is basically potted meat (usually fatty duck or pork) that's been slowly cooked with aromatics until it falls apart, then shredded, mixed with more fat, then packed into a container to be sealed with another helping of fat (again, either duck or pork). These days, it's almost as rare as a leprechaun, so I've decided to make it more accessible, super quick, healthy (but by no means less rich), and green - yes, green - because leprechauns are green. —Coco et Cocoa
Mash all ingredients together in a bowl with a fork until incorporated but still retaining some texture. You may need to season more if depending on how salty your tuna and pesto are.
Spoon into small ramekins, cover with plastic wrap and chill for an hour before serving with baguette or crackers. The oil will separate and gather at the top, which will help keep it fresh for up to two days. To be honest, though, if it's just for myself, I'll eat it right out of the mixing bowl.