Melt the butter in a large pot over medium heat, then add the onion, carrots, and celery. Cook the vegetables for about 10 minutes, stirring occasionally, until they begin to soften. Add the garlic to the pot and cook it with the vegetables for about a minute, stirring constantly, until very fragrant.
Add the wine to the pot and bring it to a simmer. Let it simmer for 2 to 3 minutes, until most of the liquid has dried up.
Sprinkle in the flour and stir well to coat the veggies. Cook the mixture for about a minute, stirring constantly.
Drizzle in the broth while stirring. Once all of the broth has been added, stir in the coconut milk, potato, green beans, thyme, and bay leaf. Raise the heat and bring the liquid to a boil, then lower the heat and let the soup simmer until the potato and green beans are tender, about 20 minutes, stirring occasionally.
Stir in the peas and corn. Let the soup simmer a minute or so longer, just to heat up the veggies you just added.
Remove the pot from heat and remove the bay leaf. Stir in the lemon juice, then season the soup with salt and pepper to taste.
Optional step: Blend a cup or two of the soup if you'd like to thicken the broth. You can transfer it to a blender, or just briefly blend it in the pot using a hand blender. Always use caution when blending hot liquids.
Ladle into bowls and serve.