Cut the avocado in half, remove the pit, and scoop out the flesh into a blender or food processor. Puree the avocado with the lime juice and season with salt. Set aside.
In a large bowl, whip crème fraiche and crema Mexicana until soft peaks form. Fold avocado puree into whipped cream gently but thoroughly.
Mix all ingredients in a blender until smooth.
Drain and rinse scallops thoroughly, pat them dry with paper towels and set aside.
Sprinkle both sides of scallops with salt.
Heat a nonstick pan over high heat and add 1 tablespoon of olive oil. The oil needs to be very hot before you add the scallops.
Place the scallops flat-side down in the hot pan. Don't overcrowd the pan, or you'll lower the pan temperature, causing the scallops to be steamed rather than seared. Cook for about 2 to 3 minutes on each side until golden and caramelized. Make sure they are caramelized before turning. Turn only once. Do not overcook or they will be rubbery.
Spoon the avocado purée into cocktail glasses.
Fill some small serving bowls with chipotle sauce.
Place one skewered scallop across the rim of each cocktail glass and serve.
Skewer them before serving for easy handling and charming presentation. For another serving idea you can serve them on miniature fried corn tortillas topped with the avocado mousse. The presentation is up to you.