
In a large cast-iron or other heavy skillet, heat oil over medium-high heat.
Add mushrooms; cook, stirring occasionally, until lightly browned, 4-6 minutes.
Add asparagus, garlic, oregano, salt and pepper; cook and stir until asparagus is crisp-tender, 2-4 minutes.
Stir in kale; cook and stir until wilted, 2-4 minutes.
Remove from heat; stir in fish sauce and vinegar.
If desired, top with sesame seeds.