Heat the oil in a small pot or Korean earthenware pot over medium-low heat. Add the gochugaru, minced garlic and scallion whites. Stir for about 1 minute until the oil turns red and smells toasty. Do not let the chili flakes darken or they turn bitter.
Stir in the gochujang and soy sauce for 20 seconds, then pour in the stock. Add the zucchini and onion and bring to a boil. Simmer for 4 minutes.
Add the shrimp and cook for 2 minutes, just until they start to curl and turn pink.
Slide in the sundubu in large spoonfuls, breaking it into chunks with your spoon. Simmer for 4 to 5 minutes until the tofu is steaming hot and the broth is bubbling again.
Taste and adjust with salt and pepper. Crack an egg into the center of each portion (or crack both into the pot), cover for 1 minute so the whites set while the yolks stay soft, and top with the scallion greens.
Serve right away in the pot or ladled into bowls, with steamed rice on the side.