Meanwhile, heat the rest of 1 tablespoon olive oil in the same pot over medium-high heat. Add onion and stir for 2 mins or until softened. Add mushroom slices and cook for 3 to 4 minutes or until just tender. Add garlic, thyme and lemon zest and cook until fragrant. Add flour and stir for 1 min. Add wine and bring to boil with stirring. Reduce heat to low. Add cream and stir until he sauce is thickened. Simmer for 2 to 3 mins.