Place the thinly sliced cucumbers and sea salt in a medium bowl and toss to combine. Let them sit for 10 to 15 minutes, allowing the salt to draw out excess moisture. Afterward, gently squeeze the cucumbers to release more liquid. Taste them—if they seem too salty, rinse briefly under water and gently squeeze out the excess moisture again. Drizzle with sesame oil, toss lightly, and set aside.

In a large mixing bowl, combine the shredded red cabbage with rice wine vinegar, sea salt, and sugar. Let the mixture sit until the cabbage begins to wilt slightly and soak up the dressing.

In a small bowl, whisk together all the Korean beef sauce ingredients and set aside. Heat a pan over medium-high heat, add the avocado oil, and cook the ground beef, breaking it into small pieces as it browns. Once the beef is nearly cooked through, stir in the chopped onions and the prepared sauce. Continue cooking for about 3 more minutes until the meat is fully cooked and the onions have softened. Remove from heat.

To serve, spoon the Korean beef filling onto warm corn tortillas. Top with the red cabbage slaw and pickled cucumbers. Garnish with optional toppings such as chopped kimchi, sesame seeds, scallions, and cilantro. Serve with lime wedges on the side.