Warm olive oil in a large pot over medium-high heat. Add onions and 1/2 tsp. salt and stir to combine. Cover, reduce heat to medium, and cook, stirring occasionally, until onions are very soft, 5 to 10 minutes; reduce heat, if necessary, to keep onions from browning.
Add garlic and cook, uncovered, until soft, about 3 minutes. Stir in paprika and cook 1 minute. Add lentils, peppers, tomatoes, and 1 1/3 cups broth. Bring to a boil, reduce heat to maintain a steady simmer, cover, and cook until lentils are extremely soft, about 30 minutes.
In 3 batches, whirl soup in a blender until very smooth, at least 3 minutes per batch. Add dry milk and vinegar to the last batch. Stir together and season with salt and vinegar to taste; add a little more broth if soup seems too thick.
Serve topped with a sprinkle of almonds and a drizzle of almond oil if you like.
Note: Nutritional analysis is per 1 1/2-cup serving.