Step #1 To Make the Dressing: Put the lime juice, sour cream, cumin, cilantro, olive oil, garlic, chili powder, jalapeno, mayonnaise, & Parmesan in the container of a mixer or food processor/blender; process until smooth.
Step #2 Refrigerate until ready to use.
Step #3 To toast the pumpkin seeds: heat the olive oil in a small skillet & add the pumpkin seeds.
Step #4 Toss continuously until the seeds are lightly toasted, about 3 mins.
Step #5 Spice up to taste with salt & let cool.
Step #6 To Assemble the Salad: Combine the lettuce, onion, tortilla chips, avocado, & dressing In a large-ish salad bowl.
Step #7 Spice up to taste with salt & pepper.
Step #8 Sprinkle top the queso fresco & toasted pumpkin seeds over the salad.