Raw Cauliflower Couscous Tabouli

1 head yellow or white cauliflower
1/2 bunch flat leaf parsley, rough chopped
1/2 packed cup fresh mint leaves, rough chopped
1 medium tomato, diced
1/2 red onion, diced
1/2 cup olive oil
1/4 cup fresh lemon juice
1 teaspoon salt, or to taste
1/2 teaspoon turmeric
1/4 teaspoon pepper, or to taste
2 drops liquid stevia extract (optional)