Thinly slice the beef brisket against the grain. Then, mince the garlic cloves.

In a pot over medium heat, add vegetable oil. Stir-fry the sliced beef and minced garlic for about 2 minutes until the beef is no longer pink.

Pour water into the pot, cover it, and let it cook for 10 minutes over medium heat to create the broth.

While the broth simmers, prepare the vegetables by dicing the potato, zucchini, and onion into ½ inch cubes.

Add the diced vegetables and Korean soybean paste (doenjang) to the pot. Stir to dissolve the paste, cover, and cook for another 10 minutes.

While the stew is cooking, cut the tofu into cubes and chop the green onion and green chili peppers.

Add the tofu, green onion, green chili peppers, and optional gochugaru to the stew. Stir gently, cover, and cook for a final 5 minutes.

The beef doenjang-jjigae is ready. Serve it hot.