While the pasta is cooking, place the buttermilk, mayonnaise and half of the lemon juice in a large mixing bowl. Drain the pasta and pour it into the mixing bowl with some water still clinging to it. Stir the pasta, then add the onion, celery, bell pepper, parsley, cheese, corn and thyme. Stir in the tuna and remaining lemon juice, adding salt and pepper to taste. Taste the pasta and adjust the seasonings.
Pasta absorbs liquid as it chills.
Taste before serving and if it seems dry or dull, refresh the flavors with a splash of lemon juice, buttermilk or small spoonful of mayonnaise, or a combination. Inc. All rights reserved.