Step 1

In a large bowl with enough lightly salted water to cover, place the cauliflower, pearl onions, red bell peppers, green bell peppers, celery and cucumbers. Soak 8 to 12 hours, or overnight.

Step 2

In a small bowl with enough lightly salted water to cover, place the carrots. Soak 8 to 12 hours, or overnight.

Step 3

In a large saucepan, place the vegetable oil, vinegar, tomato paste and pickling spice. Bring the mixture to a boil. Drain and rinse the carrots, and place them in the mixture. Boil 10 minutes.

Step 4

Drain and rinse the vegetables in the cauliflower mixture. Place them into the saucepan. Cook 10 minutes, or until the cauliflower is tender but crisp.

Step 5

Stir black olives, green olives, mushrooms and tuna into the mixture. Remove the mixture from heat. Discard the wrapped pickling spice. While still hot, transfer to sterile containers and refrigerate.