Blanch the napa cabbage briefly in boiling water.
Remove excess moisture from the tofu using a paper towel, then mash it.
Drain the oil from the tuna and place it in a bowl.
Add the mashed tofu, tuna, chopped bell pepper, salt, and pepper, then mix well.
Place the filling on the blanched napa cabbage and roll it up tightly.
Heat a pan with a little oil and sear the rolls on both sides.
Cut into bite-sized pieces and arrange on a plate.