This was just born out of playing with a range of liqueurs taking up space in my cabinet.
1 oz London Dry gin (you could bump this up to 1 1/2 oz if using a less-assertive gin)
1/2 oz triple sec (Luxardo's version has become my favorite, but any will do)
1/2 oz Pimm's Cup No. 1
1/2 oz Aperol
1 oz lime juice
Shake well and strain over fresh ice. Garnish with an orange wheel if you're feeling fancy.