Stash this light but luscious soup in the freezer for a healthy homemade meal with zero effort. No can opener required.
In a large saucepan, heat oil over medium-high. Add onion; season with salt and pepper. Cook until soft, about 5 minutes. Add broth, broccoli, potato, and 2 cups water; season generously with salt. Bring to a boil. Reduce heat, and simmer until broccoli and potato are just tender, about 4 minutes.
Working in batches, puree soup in a blender (fill it no more than halfway) and return to pot. Stir in cream and lemon juice; season with salt and pepper.
To freeze: Cool soup to room temperature. Pour about 1 1/2 cups into each of 6 airtight containers, leaving 1 inch of space at the top. Freeze up to 3 months. Thaw in microwave or overnight in refrigerator; warm over low heat.