Blend watermelon, jalapeño (I used it seeds and all!), and salt together until smooth. I like to let it blend an extra 30 seconds or so on the highest speed to get it as mixed and finely processed as possible.

Strain juice through a fine mesh sieve into a jar or cup, set aside.

Get your glassware ready and fill a cocktail shaker with ice.

Using a jigger or other measuring device, pour 2 ounces of gin and 4 ounces of watermelon juice into the shaker. Close and shake for 15 seconds moving the shaker up and down at a 45 degree angle.

Pour into martini glass, through a fine mesh sieve, and garnish with a paper thin slice of fresh jalapeño.

Repeat for each martini, changing ice as needed between cocktails. I found I can make two martinis with the same ice, then I need to dump it and start fresh so the drinks don't get watered down.