01 -
In a medium mixing bowl, combine ground beef, soy sauce, brown sugar, minced garlic, grated ginger, and gochugaru. Mix gently to blend the ingredients evenly, taking care not to overwork the meat.
02 -
Spread the seasoned beef mixture evenly into the slow cooker insert. Drizzle sesame oil over the beef. Cover with the lid.
03 -
Cook on low heat for 4 to 5 hours. Stir once halfway through the cooking time if possible, until the beef becomes tender and develops deep flavor.
04 -
While the beef cooks, thinly slice cucumber and transfer to a bowl. Add rice vinegar, granulated sugar, salt, and optional red pepper flakes. Toss to coat thoroughly. Let the cucumbers marinate for at least 10 minutes.
05 -
Shortly before serving, heat tortillas in a dry skillet over medium heat for 30 seconds per side, or wrap in foil and warm in a 350°F oven for 5 to 7 minutes.
06 -
Stir the sliced green onions into the cooked beef. Taste and adjust seasoning if needed.
07 -
Spoon cooked beef onto warmed tortillas. Top generously with pickled cucumber slices. Serve immediately, adding optional garnishes like sliced radishes, fresh cilantro, or a drizzle of sriracha mayo if desired.