Snap off and discard woody ends of asparagus spears; peel stalks if desired.

Heat olive oil and butter in a skillet over medium-high heat; when foaming subsides, add shallots and cook, stirring, for 1 minute. Add asparagus in a single layer, reduce heat to medium, cover, and cook, stirring often, until just tender. Sprinkle with lemon juice and add salt and pepper to taste. Serve hot or cold.