In a small bowl, mix together the olive oil, lemon juice, garlic, thyme, crushed red pepper and salt. Set the dressing aside.
Wash the Brussels sprouts well. Trim off the bottom of the Brussels sprouts and remove any damaged or wilted leaves. Cut in half.
Bring a medium pot of water to a boil. Once the water is boiling, add 1 teaspoon salt. Add the Brussels sprouts to the boiling, salted water. Boil them uncovered until tender, about 5-6 minutes. Then drain and rinse under cool water. Drain well.
Place the Brussels sprouts, parsley and coriander in a large bowl. Pour the dressing over them and gently toss together. Taste and adjust seasoning.
Cover and marinate in refrigerator overnight, stirring occasionally.