Thinly slice 1 small red onion. Add ½ to a small bowl and season with 1 tsp salt. Toss gently to coat then set aside to macerate. Meanwhile, transfer contents of 1 186mL can chipotle peppers (sauce and all) to a cutting board and finely chop until a thick paste forms. Transfer to a medium bowl, add 3/4 cup yogurt and 1/4 cup mayonnaise, and mix until well-incorporated. Back in the small bowl add 1/4 cup white vinegar, 2 tbsp agave syrup and ¼ cup water. Toss and let sit to pickle while you cook the shrimp.
Transfer 340g shrimp to a large plate, pat dry using paper towel and season with 1/2 tsp salt. Heat a large pan on medium-high. Once hot, add 2 tbsp neutral oil and the remaining sliced onion. Cook, occasionally stirring, until soft but not brown, about 5 minutes. Add shrimp and season with another 1/2 tsp salt. Cook until pink and starting to brown on one side, about 3 minutes, then flip and continue cooking until pink all over, about 2 more minutes. Add the creamy chipotle sauce and bring to a light simmer, continue cooking until the sauce is thickened and the shrimp are opaque in the middle, about 5 minutes.
Transfer to a plate and wipe the pan using paper towel. Place the pan back on the burner and heat on medium-low. Lay down 1-2 tortillas (depending on the size of your pan) then top with a handful of grated Cotija cheese. Cover and cook for 1-2 minutes, or until melted. Top each tortilla with creamy chipotle shrimp, some pickled onions and a squeeze of lime.
