Open the can of tuna with a can opener and drain excess liquid. Flake the tuna into a large mixing bowl using a fork, breaking it into small pieces.
Use a sharp knife and cutting board to thinly slice the radishes into rounds. Arrange slices neatly for visual uniformity.
Add the sliced radishes to the bowl with the flaked tuna. Pour in the olive oil, lemon juice, and season with salt and black pepper. Gently toss everything together until evenly combined and radish slices are coated.
Observe the mixture for a vibrant contrast of colors and a crunchy texture from the radishes. Check seasoning, adding more salt, pepper, or lemon juice as desired.
Serve immediately or chill for 10 minutes in the refrigerator to allow flavors to meld. Plate the salad in bowls or on a platter, garnished with additional radish slices if desired.
