Well here it is:
1. Go in your fridge and take out your shriveling strawberries and you limp rhubarb.
2. Hull the berries, chop the rhubarb and throw in a pot with a touch of sugar and a bit of water (these are precise measurements - I hope you're taking notes)
3. Simmer, simmer, simmer until everything is super soft
4. Smash, smash, smash
5. Push through sieve (you could probably skip 4 and 5 and just throw everything in a blender!)
7. Put ice cubes, gin, a teaspoon of sugar (depending on how sweet you made your puree you could leave this out) and lime juice in a shaker.
8. Shake, shake, shake
9. Poor into a glass, top with club soda.
This would probably be extra tasty with the addition of some herbs like mint or basil. If I had some ginger I would have simmered it with the strawberries and rhubarb and pulled it out before I started smashing and sieve-ing. It certainly doesn't NEED anything else though - it's pretty delicious as-is.
PS - Don't feel like simmering and and smashing and waiting for the whole thing to get cold? I don't blame you. Instead skip the rhubarb, take a few of those strawberries and muddle them with a tsp of sugar and some lime, shake with ice and gin, pour into a glass, top with soda and drink up. Mmm.