Preheat oven to 425F.

Line a large baking pan with parchment paper.

Bring water, milk, butter and ¹/₂ teaspoon salt to a boil in a medium pan over medium heat.

Lower heat; add flour and stir with wooden spoon until mixture comes together, dries out and pulls away from sides of pan.

Remove from heat and cool until warm.

Add eggs about one at a time; beat until well incorporated and mixture becomes smooth batter. Fold in cheese.

Spoon batter into a pastry bag; pipe into four (about 6 inches long and 1.5 inches in diameter) logs, 2 inches apart on prepared baking pan. Bake for 12 minutes.

Lower oven temperature to 350°F; continue baking until gougeres are golden brown and sound hollow when tapped, about 20-25 minutes more.

Cool gougeres completely; halve lengthwise.

Meanwhile, in a medium bowl, toss radish, carrots, cucumber, vinegar, sugar and ¹/₄ teaspoon salt.

Chill for at least 30 minutes. In another bowl, mix together mayonnaise and mustard. Stir in crab meat and green onion. Chill for 30 minutes.

Stuff bottom gougere halves with crab mixture and pickled vegetables.

Garnish with jalapeno slices and cilantro sprigs. Place remaining gougere halves on top.