1/3 cup very coarsely chopped red onion
About 3 tbsp. olive oil, divided
3/4 teaspoon kosher salt, divided
1 large poblano chile
1 large Roma tomato
1 cup diced nopales (see "Nopales Basics," below)
6 large eggs
1/4 teaspoon pepper
1/2 teaspoon ground cumin
1/2 cup shredded sharp cheddar cheese
Hot sauce
Preheat oven to 475°. Line a sheet pan with parchment paper. On parchment, toss potato, onion, 1/2 tbsp. oil, and 1/4 tsp. salt. Set chile and tomato in corner of sheet pan. Bake, turning vegetables once, until browned, about 20 minutes. In a frying pan, sauté nopales over high heat with 1/2 tbsp. oil and 1/4 tsp. salt until pan is mostly dry, 3 to 6 minutes, then reduce heat and cook until barely tender, 3 to 4 minutes more. Set aside. Peel, stem, and seed chile; peel tomato. Chop both. In a bowl, whisk eggs with remaining 1/4 tsp. salt and the pepper. Heat a large skillet over medium-high heat. Add remaining 2 tbsp. oil and the cumin; cook until fragrant, 1 minute. Stir in potato mixture, chile, tomato, and nopales. Cook until hot. Pour in eggs and cook, stirring often, until set, 3 minutes. Sprinkle cheese on top; stir a few times until it melts. Serve with hot sauce.
Nopales Basics: Some supermarkets and Latino markets sell cactus with the spines, and others sell it de-stickered and ready to use--whole or cut up. When buying whole pads, look for ones that are smooth, crisp, and small to medium size. To remove spines from pads, put on dish gloves. Scrape a knife almost flat down the length of both sides of pads to shave off spines and barbed, fuzzy dots. Pare rims with a vegetable peeler. Trim bases; rinse pads. Once nopales hit the heat, they release a sticky juice (like okra), but it cooks off.