Preheat the oven to the “keep warm” setting (170°F).
Drain the tuna well and flake it with a fork in a medium bowl.
Add mayonnaise, Dijon mustard, minced garlic, eggs, kosher salt, black pepper, and parsley to the tuna and mix well.
Heat olive oil in a large nonstick skillet over medium heat.
Using a 4-tablespoon scoop or measuring cup, form four mounds of the tuna mixture in the skillet.
Gently flatten the mounds with the back of a fork.
Cook the patties until golden brown, about 3 minutes per side.
Transfer cooked patties to the warm oven while you fry the second batch.
Serve immediately.