Though Denmark travel guides characterize smørrebrød as an open-face sandwich, food editors Melissa Roberts and Maggie Ruggiero found that this national favorite is somewhere between that and an oversize canapé, with a few carefully chosen ingredients arranged generously on top (often to the point where the bread is no longer even visible). Here, whittled down to bite-size, it's an elegant hors d'oeuvre that retains the Danish spirit; caraway butter complements the classic rye base, and lightly fried beets and sweet onion are an alluring counterpoint to the smoked salmon.
Frizzled beets can be made 1 day ahead and cooled completely, uncovered, then kept in an airtight container at room temperature. Recrisp up to 2 hours ahead on a baking sheet in a 300°F oven 3 to 5 minutes. If beets are not crisp once cooled, return to oven briefly.