1.Heat the oven at 180°C.
2.In a deep bowl, mix the tuna with the mayonnaise and lemon juice well until they are incorporated.
3.Cut the edges of the toast, and then roll them out with the rolling pin.
4.Using the circular cutter, cut the toast slices, then place them in small-sized cupcakes molds and put them in the oven for 5 to 7 minutes to brown.
5.Fill the browned toast with the prepared tuna filling, and then serve it.