Drain the tuna. Peel and chop the onion. Puree tuna and diced onion and mix with mayonnaise. Season to taste with salt, pepper and lemon juice. Remove the crusts from the sandwich slices. Spread 6 slices of wheat toast with tuna cream, 6 slices of wholemeal toast with cream cheese. Wash, clean and slice the tomatoes.
Clean and wash cucumber and bell peppers and cut into fine slices or rings. Wash parsley, pluck off leaves. Remove radicchio leaves from the stalk, wash and drain. Place salmon on the sandwich slices coated with cream cheese. Spread the remaining ingredients as desired on the coated sandwiches. Cover each sandwich with the appropriate slice of toast and wrap in foil for transport