Shrimp Ceviche "cocktail"

From Rick Bayless's "Mexico One Plate at a Time". I haven't tried it yet, posting it here for safekeeping.

• Ready In: 1 hr 10 mins
• Serves: 6
• Yields: 3 cup

Ingredients

• 1⁄2 cup fresh lime juice
• 2  tablespoons fresh lime juice
• 1  lb raw shrimp in shells (preferably 41/50)
• 1⁄2 medium  white onion, chopped into 1/4 in pieces
• 1⁄3 cup cilantro, fresh, plus several sprigs for garnish
• 1⁄2 cup ketchup
• 1 -2  tablespoon  vinegary mexican bottled  hot sauce (Tamazula, Valentina or Bufalo)
• 2  tablespoons extra virgin olive oil (optional but recommended to smooth out sharpness)
• 1  cup cucumbers or 1  cup jicama, peeled and diced
• 1  avocado, peeled, pitted and cubed
•  salt
•  lime (to garnish)
•  tostadas, tortilla chips or   saltine, for serving

Directions

1. Bring 1 qt salted water to a boil and add 2 tbsp of the lime juice.
2. Scoop in the shrimp, cover and let the water return to the boil.
3. Immediately remove from the heat, set the lid askew and pour off all the liquid.
4. Replace the cover and let the shrimp steam off the heat for 10 minutes. Spread out the shrimp in a large glass or stainless steel bowl to cool completely.
5. Peel and devein the shrimp if you wish.
6. Toss the remaining shrimp with the remaining 1/2 cup lime juice, cover and refrigerate for about an hour.
7. In a small strainer, rinse the onion under cold water, then shake off the excess liquid.
8. Add to the shrimp bowl along with the cilantro, ketchup, hot sauce, optional olive oil, cucumber and/or jicama and avocado.
9. Taste and season with salt, usually about 1/2 teaspoon.
10. Cover and refrigerate if not serving immediately.
11. Spoon the ceviche into sundae glasses, martini glasses, or small bowls.
12. Garnish with sprigs of cilantro and slices of lime.
13. Serve with tostadas, tortilla chips or saltines to enjoy alongside.