This dish doubles as an appetizer or a main. Whip up the aioli ahead and refrigerate until ready to pack for your picnic. Slip marinated and skewered prawns into a tightly sealed container and pack on ice to grill on location. It’s a delicious and easy midday snack.
Per serving:
In bowl, place cashews, cover with hot water, and set aside to soak until water has cooled. Drain well and place cashews in high-speed blender along with remaining aioli ingredients. Whirl until blended and smooth, scraping down sides of bowl occasionally. Add some water, if needed, to make aioli nice and creamy. Taste and add more lemon, chipotle, or ground cumin if you wish. Chipotle Aioli can be stored in a tightly covered jar in the refrigerator for up to 1 week.
For prawns, in small food processor or blender, combine olive oil, lemon juice, garlic, oregano, rosemary, salt, and pepper. Whirl until thoroughly blended. Place in large bowl.
Peel and devein prawns, leaving tails intact. Pat dry. Add to olive oil mixture and gently massage into prawns. Refrigerate and marinate for 30 minutes to 1 hour. Soak 6 wooden skewers in water for 30 minutes.
Grease barbecue grill and preheat to medium high. Thread several prawns onto each soaked skewer. Alternate with water chestnuts and chunks of pepper, if you wish. Brush with a little added olive oil, if including vegetables on skewers.
Grill prawns about 5 in (13 cm) from direct heat for 1 to 2 minutes per side. Serve hot or cold with Chipotle Aioli.
Want a speedy traditional Chipotle Aioli with half the fuss? Stir a splash of lemon juice, maple syrup, minced chipotle in adobo sauce and generous pinches of ground cumin into 1/2 cup (125 mL) prepared mayonnaise. Whisk to blend. Aioli can be refrigerated for a few days.