Brown the beef: Pat the beef dry and season with salt and pepper. Heat 1 tbsp olive oil in a small Dutch oven over medium-high heat. Brown in batches, about 3 minutes per side, then set aside.
Sauté aromatics: In the same pot, cook the mushrooms, onion, and bell pepper until softened, about 7 minutes. Add garlic and ginger and cook 1 minute more.
Build the fond: Stir in tomato paste, turmeric, and smoked paprika and cook 1 minute. Pour in the red wine and scrape up the browned bits until reduced by about half.
Simmer: Return the beef to the pot with the stock and thyme. Bring to a boil, reduce to a low simmer, cover, and cook 1 ½ to 2 hours, until the beef is fork-tender.
Add sweet potato and lentils: Stir them in and simmer uncovered 20 to 25 minutes, until tender and thickened.
Stir in depth: Remove from heat. Whisk the miso with a ladle of hot broth, then stir it in. Melt in the dark chocolate. Discard the thyme sprigs.
Finish and serve: Fold in the spinach and lemon juice until wilted. Taste and adjust salt. Ladle into bowls and top with pumpkin seeds, parsley, a drizzle of olive oil, and a squeeze of lemon.
