Dice the tomatoes, sweet onion, red onion, and jalapeño very evenly, then combine in a bowl with the lime juice, lime zest, olive oil, salt, and black pepper. Let it sit for 10–15 minutes, then taste and adjust seasoning. Before using on the nachos, lightly drain off excess liquid. This matters. Watery pico will flood the chips and kill the whole tray. Dicing every component to a genuinely even size isn't just visual — uniform pieces mean the pico's flavour is consistent bite to bite, and the short rest afterward lets the salt draw out excess tomato liquid before it ever reaches the hot tray.

Mash the avocados in a bowl until partly smooth but still chunky. Fold in the red onion, jalapeño, garlic, lime juice, cilantro, cumin, salt, black pepper, and green Tabasco if using. Keep it thick and spoonable, not loose or fully smooth. The guacamole should sit in visible green mounds on top of the nachos, not spread like a sauce. Mashing only partly, rather than to a completely smooth purée, is what gives the guacamole enough body to hold its shape as a distinct mound once spooned onto the hot tray, rather than sinking in and disappearing among the other toppings.

Heat a large skillet over medium-high heat. Add the ground beef and cook, breaking it up, for 4–5 minutes until it starts browning properly. Add the diced onion and continue cooking until the beef develops dark brown edges and the onion softens, about 4 more minutes. Add the garlic, salt, cumin, chili powder, smoked paprika, oregano, black pepper, and tomato paste. Cook for 1–2 minutes, stirring constantly, until fragrant and the tomato paste darkens slightly. If the mixture looks too dry while the seasonings bloom, add 30ml water only as needed. Finish with lime juice. The beef should be hot, fragrant, and slightly crisp in places, not wet or saucy. If there is excess grease pooling in the pan, spoon some off. Greasy beef will slide over the chips and make the tray heavy and soggy. Browning the beef hard before adding the onion, rather than combining everything at once, is what produces the dark, crisp edges specified here — beef added to a pan already crowded with onion releases moisture and steams rather than developing real colour.

Preheat the oven to 220°C / 425°F or set the broiler on high. Use a large sheet pan, ovenproof platter, or skillet so the chips can sit in a broad, mostly single layer. A broad, shallow layer rather than a deep pile is what allows the oven's heat to reach and melt cheese across the whole tray evenly — a deep, crowded pile traps heat unevenly and leaves chips at the bottom soggy while the top barely warms through.

Spread the tortilla chips out in an even generous layer. Scatter the shredded Mexican cheese blend over the chips so it reaches across most of the surface, but still leaves some golden chips visible. Scatter the hot seasoned ground beef evenly over the cheese. This order matters here: nachos, cheese, then ground beef. Putting the beef directly on bare chips everywhere can weigh them down too fast, while the cheese helps lock the base together. The melting cheese layer functions almost structurally here, fusing to the chips beneath it as it melts and giving the heavier beef scattered on top something stable to sit on rather than direct, weighty contact with the chips themselves.

Bake or broil for 3–6 minutes, just until the cheese is fully melted and bubbling. Watch closely. You want melted cheese and hot chips, not burned chip tips or dried-out beef. This is a short, high-heat stage specifically for melting rather than cooking anything further — both the beef and the chips are already fully prepared, so the oven's only job here is bringing the cheese to a fully melted, bubbling state as quickly as possible.

Remove from the oven and immediately scatter the drained pico de gallo over the top. Add visible spoonfuls of guacamole across the tray. Add one spoonful of sour cream per serving, spaced clearly so the white mounds stay visible. Finish with thin jalapeño slices scattered over everything. Add a little cilantro if wanted and serve with lime wedges if using. Adding every cold topping only after the tray leaves the oven, rather than baking any of them, is what keeps the pico, guacamole, and sour cream tasting genuinely fresh and looking visually distinct against the hot, melted cheese beneath them.

Serve immediately while the chips are still crisp, the cheese is hot and melted, and the cold toppings stay fresh and distinct. Loaded nachos have essentially no holding window once fully assembled — the chips begin softening under the combined weight and moisture of every topping within minutes, so serving without delay is what preserves the crisp-hot-cool contrast the whole tray is built around.