Sautee the veggies in 2 Tbsp fat of your choice. If using bacon, I fry up diced bacon till crispy and reserve to add back at the end. Don’t brown the veggies. When they are soft, add the rest of the fat and the flour. Stir constantly over med-low heat – you want to get rid of the raw flour taste but not burn it.
Add 1 cup of tomato juice while stirring. This will get rather thick. I do this first bc I find it’s easier to prevent lumps this way. Once everything is smooth, slowly add the rest of the juice. Bring to a boil and the soup will be slightly thick and creamy.
I like to dice up bacon and fry it crispy to render the fat. Remove and reserve the crispy bacon. Try to not eat it all while making the rest of the soup. Add the bacon bits back in at the end or sprinkle them on top of each bowl.
If you like it chunkier, you can use crushed tomatoes instead of juice. I like using half chicken or veggie stock with half crushed tomatoes.
I’ve done this with an all-purpose gluten free flour mix. I don’t care for using all starch or all rice flour, but a mix works well.