Pulse the walnuts in a food processor until finely crumbled, four or five times (be careful not to over pulse!).
Transfer paprika, chili, and cumin into a saucepan over medium heat and toast for 30 seconds, stirring often. Add walnuts and salt and toss. Add water and lime juice and stir until completely coated. Remove from heat and set aside.
Add all salsa ingredients into a bowl and toss to combine. Season with salt and pepper.
Warm the tortillas in a saucepan over medium heat for 10 seconds. Double up the tortillas and place 1/4 of the walnut meat and peach salsa in them. Repeat with the remaining tortillas. Top with avocado, cabbage, and yogurt or sour cream (if using). Serve warm.