Italian rice salad - insalata di riso

1 1/2 cups (300 g) parboiled rice (the grains should not stick)
Either: An 8-ounce (200 g) can tuna, drained and shredded, and four canned sardines, boned and shredded
Or: 1 hot dog, cooked and sliced, and a 1/4 pound (100 g) slab of ham, diced
1/4 pound (100 g) Fontina or Swiss cheese, diced
1/4 cup pitted, sliced black olives
1 pickled bell pepper, diced
2 ripe, peeled, seeded tomatoes, diced (optional)
1/4 cup mushrooms in oil, diced (optional)
1-2 tablespoons cooked peas (optional)
1/4 cup pickled button onions (optional)
2 hard boiled eggs, sliced or quartered (optional)
1 tablespoon rinsed salted or pickled capers (optional)
2 pickled artichoke hearts, sliced (optional)
1 tablespoon minced parsley
1/4 cup olive oil or mayonnaise
A tablespoon of lemon juice
Salt and pepper to taste