In a dutch oven on your stovetop heat at medium high and add your olive oil. When hot add onions and saute for 5 minutes to soften. (if you want to add meat, I would use ground spicy sausage. If adding do so now and cook until it is no longer pink)
Then add fennel, garlic, asparagus and saute for 1-2 more minutes.
Pour in broth, add dill, salt and pepper and lemon juice. Stir.
Bring mixture to a boil and simmer for 15 minutes until vegetables are as tender as you'd like them to be.
Add fresh spinach leaves or kale and submerge into liquid. Cook for 5 more minutes so they soften. Serve topped with croutons and/or parmesan cheese.
Instant Pot instructions: Saute olive oil and onions first, if you want to add diced kielbasa do so at this time. When onions are softened turn pot off. Add all other ingredients, stir. Lock lid and close steam valve and cook on high pressure for 1 minute. Do a quick release. If not tender enough for your liking, set to saute and bubble until they are as tender as you'd like (shouldn't be necessary).