Prepare the Puntarelle: Wash and trim the puntarelle. If the stalks are thick, slice them thinly lengthwise. If using the core, soak the shredded pieces in ice water to encourage curling.
Prepare the Potatoes: Peel and dice the potatoes into 1-inch cubes.
Sauté Aromatics: In a pot, heat olive oil over medium heat. Add minced garlic and red pepper flakes. Sauté for about 1 minute until fragrant, being careful not to burn the garlic.
Cook Potatoes: Add the diced potatoes to the pot and stir to coat them with the garlic-infused oil. Cook for about 5 minutes, stirring occasionally, until the potatoes start to soften slightly.
Add Broth and Simmer: Pour in the vegetable broth. Bring to a simmer, then reduce heat, cover, and cook for about 15 minutes, or until the potatoes are tender.
Add Puntarelle: Add the puntarelle to the pot. Stir well and cook for another 5-7 minutes, until the puntarelle is tender-crisp.
Prepare Gremolata: While the stew simmers, prepare the gremolata. In a small bowl, combine chopped parsley, lemon zest, and a squeeze of lemon juice.
Season and Serve: Season the stew with salt and black pepper to taste. Stir in a bit more lemon juice if desired.
Serve: Ladle the puntarelle and potato stew into bowls. Top each serving with a generous spoonful of gremolata.