Heat the stock in a medium saucepan and keep it simmering over low heat.
In a medium pot or Dutch oven, heat the butter and olive oil over medium heat.
Add the diced onion, poblano pepper, and minced garlic to the pot. Sauté for about 5 minutes, stirring occasionally, until the vegetables are softened.
Stir in the saffron threads and Arborio rice, ensuring all grains are coated with the butter and oil mixture.
Pour in the dry white wine and cook for about 5 minutes, stirring constantly, until most of the liquid has been absorbed.
Begin adding the warm stock to the rice mixture, about 1/2 cup at a time, stirring frequently.
Continue adding stock gradually, allowing each addition to be absorbed before adding more. Cook the risotto for about 25-30 minutes, or until the rice is al dente.
Once the rice is cooked, stir in the creme fraiche, salt, and black pepper, adjusting seasoning to taste.
Gently fold in the lump crab meat, ensuring it is evenly distributed throughout the risotto. Cook for an additional 2 minutes to warm the crab meat.
If needed, add a little more simmering stock to achieve the desired creamy consistency.
Serve the lump crab risotto hot, garnished with chopped chives and a sprinkle of lemon zest.