Place the avocado in a bowl and mash. Leave some chunks here and there.
Stir in sour cream, salsa, ½ squeezed lime and cayenne pepper. Add salt, to taste.
Scrape the guacamole into a serving dish, and squeeze fresh lime juice on top. Garnish with more fresh salsa. Serve immediately.
Notes
If serving later (should be served same day), cover with plastic wrap and press the plastic wrap to the guacamole, so it's touching the guacamole. This will prevent air from coming in and turning the top of the guacamole brown.