I really like the combination of these ingredients, so if you have access to things like green garlic and fresh fennel, please use them. But like most soups, you can play around. As for the vegetables, if you can't find one of the ones I list, use something nice. Spinach is good, turnip or mustard greens better. Arugula instead of parsley is a good alternative, too. Play with it.
Salt the venison well and brown it in batches over medium-high heat. Remove the meat as it browns and set aside. When the meat is browned, add the white parts of the onions and garlic stalks, as well as the stalk part of the fennel; leave the fronds for later. Cook the vegetables over medium heat, stirring often, until they are soft, about 6 to 8 minutes. Sprinkle some salt over them.
Add the tomato paste and mix well. Cook this a minute or two, then add the water and stir until it incorporates with the tomato paste. Bring this to a boil and add the ouzo and chicken broth, then the oregano. Return the venison and any juices that have collected to the pot. Simmer this gently until the venison is tender, about 2 hours, maybe 3 for an old animal.
When the venison is tender, add the lemon zest, parsley, green parts of the onions and fronds from the fennel and cook for a few minutes to wilt the vegetables. Add black pepper and any salt the stew might need and serve with the lemon juice on the side so everyone can add it to their liking.
Notes
One tip:Drizzle some really special olive oil over the bowl when you serve. It adds a lot. Serve this stew with crusty bread and a good red wine.