In a large bowl, combine lemon juice and zest, olive oil, apple cider vinegar, black pepper, Cajun seasoning, dry mustard, yellow mustard seeds, and garlic. Mix thoroughly.
Bring a medium saucepan of water and a pinch of salt to a boil over medium-high heat.
Add shrimp to boiling water and cook for 90 seconds or until just pink. Do not overcook. Drain and shock the shrimp in ice water.
Add shrimp and the remaining ingredients to the seasoned vinegar and oil mixture. Mix in very thoroughly, cover, and refrigerate for at least 6 hours to overnight.