Heat a skillet over medium-high heat. Add oil and garlic. Add shrimp and cook shrimp until tender (about 30 seconds of each side). Season with fresh cracked pepper and a dash of sea salt.
Add mustard greens, sesame oil, fish sauce or soy sauce. Cook until the mutard greens are slightly tender or slightly wilted (about 30 sec – 1 min.) For broader and tougher mustard leaves, cook a little longer until the greens are tender.
Add fresh cracked black pepper and taste for seasonings. Add additional salt if needed. Serve warm.