Preheat the oven to the broil setting and position the rack in the upper third of the oven.
Quarter the bell peppers lengthwise; remove and discard the stems, seeds, and membranes. Slice the quarters crosswise into small strips and transfer to a medium bowl.
Quarter the jalapeño peppers lengthwise; remove and discard the stems, seeds, and membranes. Finely dice the peppers and add to the bowl with the bell peppers.
Preheat an ovenproof skillet over medium heat.
Trim off and discard the ends of the onion and remove the outer layer; quarter the onion lengthwise, then thinly slice crosswise. Add to the bowl with the peppers.
1 medium red onion
Trim off and discard the ends of the green onions; cut the onions crosswise into ¼-inch pieces at an angle. Transfer to a small bowl.
Once the skillet is hot, add olive oil and swirl to coat the bottom.
2 tbsp extra virgin olive oil
Add the peppers, onion, and about ¾ of the green onions (save the rest for garnishing) to the skillet; season with chili powder, cumin, salt, and pepper. Cook, stirring frequently, until the vegetables have softened, 4 to 6 minutes.
1 tsp chili powder
½ tsp cumin
1 tsp salt
½ tsp black pepper
Coarsely grate about 1 cup of cheddar.
½ (8 oz) block cheddar cheese
In a large bowl, combine and whisk together the cheddar, eggs, water, salt, and pepper.
4 tbsp water
½ tsp salt
¼ tsp black pepper
Pour the egg mixture into the skillet. While tilting the skillet with one hand, lift up the edges of the frittata with a spatula and let the eggs run underneath during the first few minutes of cooking. Cook until most of the frittata is set, but the top is still runny, 4 to 5 minutes.
Halve the avocados lengthwise and twist the halves to separate, then remove the pit with a knife or spoon; thinly slice the flesh crosswise (without piercing the skin) and scoop out.
Transfer the skillet to the oven and broil until the top is set and lightly browned, 2 to 3 minutes.
To serve, separate the frittata into wedges and divide between plates; top with avocado slices and remaining green onions. Enjoy!