Gather all ingredients before starting the recipe.
Open 1 can tuna packed in oil and drain, reserving the oil.
Slice 1 romaine heart into 1/2" slices and add to a medium mixing bowl.
Slice 1/3 red onion into thin slices cut 1/2 green bell pepper into 1/2" pieces and slice 6-8 baby plum tomatoes into halves. Toss with the prepared lettuce and season with kosher salt and freshly ground black pepper.
Squeeze 1/2 lemon into salad mixture and drizzle 1 to 2 tablespoons of oil from tuna and add the tuna in large crumbles and toss to combine.
Devide the salad between two serving plates and garnish with slices from 3 hardboiled eggs and a few anchovy fillets.