Yes, you can cook the fajitas on high heat instead of low heat in the slow cooker. However, you will need to adjust the cooking time accordingly. Typically, a recipe that calls for cooking on low for 6-8 hours can be cooked on high for approximately 3-4 hours. Keep in mind that cooking on high may result in slightly different texture and less tender meat than when cooked on low heat.
Here's a general guideline:
- **Low Heat:** Cook for 6-8 hours
- **High Heat:** Cook for 3-4 hours
Always check your specific slow cooker's manual as some models may vary in temperature settings. Additionally, ensure that the meat reaches a safe internal temperature before serving; for chicken fajitas, this would be an internal temperature of at least 165°F (74°C), and for beef fajitas, at least 145°F (63°C) with a three-minute rest time.
Remember to cut your vegetables into uniform sizes to ensure even cooking and consider adding them later in the cooking process if you prefer them to retain more texture.