Heat a 12-inch non-stick skillet over medium high heat until oil is hot. Add asparagus and salt and saute turning frequently until just getting tender, about 5 minutes. Remove asparagus to a plate.
Return skillet to heat, and melt butter. Add leek, and cook until just tender, about 2 minutes. Add spinach and peas, season with remaining 1/2 teaspoon salt and the pepper; cover, and cook until spinach is wilted and peas are tender, about 3 minutes. Turn the vegetables out of the skillet over asparagus, and serve immediately.