Heat oil in large pot over medium; sauté onion 5 minutes until softened. Add garlic; cook 1-2 minutes until fragrant, stirring frequently to prevent burning.
Add broth, beans, rosemary, oregano, salt, pepper, and pepper flakes; boil, reduce heat, and simmer 10 minutes.
Gently mash about one-third of beans against pot side with wooden spoon back to thicken soup.
Stir in kale well; simmer 8-10 minutes until tender and wilted.
Remove from heat; stir in lemon juice. Taste; adjust seasoning as needed and serve.