Preheat broiler with the top rack 6 inches from the heat source. Coarsely chop onion. Chop pineapple into 1/2" chunks. Coarsely chop cilantro leaves and stems. Finely chop 2 large garlic cloves, keep one whole for guac.

3. Broil onion and pineapple

On a rimmed baking sheet, toss onions and pineapple with 1 tablespoon oil; season with salt and pepper. Broil on top oven rack until tender, about 8-10 minutes (watch closely as broilers vary).

4. Season shrimp

Rinse shrimp, then pat very dry. Transfer to a medium bowl and toss with chopped garlic, 2 teaspoons oil, and 2 teaspoon of taco seasoning.

5. Broil shrimp

Place shrimp on baking sheet with onions and pineapple. Broil on top oven rack until shrimp are pink and cooked through, and vegetables are deeply browned in spots, about 3–4 minutes (watch closely).

6. Prepare guacamole

Run full garlic clove over the bottom of mortar or bowl. Halve avocados and add to bowl. Zest one lime, salt and pepper to taste. Use pestle to mash avocados. 

6. Finish & serve

In a small bowl, slightly thin  sour cream adding 1 teaspoon water at a time, as needed. Season to taste with salt and pepper. Toast tortillas over a flame (or under the broiler on a sheet of foil), turning frequently, until warm, 10–15 seconds per side. Wrap in foil to keep warm. (NOT NEEDED WITH JICAMA TORTILLAS) Serve shrimp. onions and pineapple with guacamole, sour cream and tortillas. Enjoy!