Melt the grease by microwaving it in a large bowl for a minute. If it isn’t all melted, don’t worry about it. Add the veg, cover, microwave for ~3 minutes. By this point the grease should be melted – you should be looking at some well-cooked veg in a small pool of grease. Stir in the flour and let that sit a minute, then add the milk and beer. Stir well. Microwave another 2 minutes, uncovered. You should now have a thick, creamy soup. If it’s too thick, add a little more milk. Season with salt & pepper.