For the cauliflower: Preheat the oven to 400 degrees F.
Combine the cauliflower, olive oil, garlic and salt in a large bowl. Place in an ovenproof skillet or rimmed baking sheet and roast until golden and tender, about 20 minutes.
For the saffron beurre blanc: Combine the white wine, cream, garlic, olive oil and lemon juice in a medium skillet over medium heat. Bring to a low simmer, then add the salt and saffron. Slowly whisk in the butter, one piece at a time, to emulsify into a sauce. Pour the sauce through a strainer and set aside.
Arrange the roasted cauliflower on a platter. Place the cilantro around the cauliflower. Dot with sriracha (more or less to your taste). Drizzle with a few tablespoons beurre blanc (extra beurre blanc will keep in the refrigerator up to 2 days).