Preheat the oven to 425°F (220°C). Line two baking sheets with parchment paper or a silicone mat and position oven racks to allow even browning. A hot oven and unobstructed air flow will crisp the tortillas quickly without drying out the filling.

Blanch the green beans: Bring a medium pot of salted water to a boil, add the trimmed and cut green beans and cook 2 minutes until bright green and slightly tender. Immediately transfer to an ice bath to stop cooking and preserve color and crunch. Blanching keeps the beans vivid and prevents them from going mushy when baked inside the taquito.

Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add the diced onion and sauté 3–4 minutes until translucent and slightly caramelized — this develops sweet savory flavor that complements the beef. Add the garlic and cook 30 seconds to 1 minute until aromatic; don't let it brown to avoid bitterness.

Add the ground beef to the skillet, breaking it up with a spatula. Increase heat briefly to medium-high to encourage browning (the Maillard reaction) — brown beef develops deeper savory flavor than simply simmering. Cook until there is no pink, about 6–8 minutes. Season with 3/4 teaspoon salt, 1/2 teaspoon black pepper, cumin, chili powder and smoked paprika; cook 1–2 minutes more to toast the spices and fully bloom their aromatics into the meat.

Drain any excess fat from the skillet (leave a tablespoon for flavor if desired). Stir the blanched green beans into the beef, taste and adjust salt & pepper. The beans add texture and a fresh counterpoint to the rich beef; chopping them small ensures every taquito has a balance of filling.

Warm the corn tortillas so they roll without cracking: stack them, cover with a damp paper towel and microwave 30–45 seconds, or heat in a dry skillet 20–30 seconds per side. Warming relaxes the tortillas and prevents splitting.

Assemble the taquitos: Place a tortilla on a work surface, spoon about 2 tablespoons of the beef-and-bean mixture along the lower third of the tortilla, and sprinkle about 1 tablespoon of shredded cheese over the filling. Roll tightly and place seam-side down on a prepared baking sheet. Repeat with remaining tortillas — tight rolling keeps them from unrolling while baking and gives a crisp exterior.

Brush or lightly spray each taquito with remaining olive oil (about 1 tbsp total for the batch) and sprinkle a pinch of salt over the tops. Brushing with oil promotes deep golden browning in the oven; a light coating is enough to crisp without deep-frying.

Bake on the center rack at 425°F (220°C) for 14–18 minutes, turning the taquitos once at the 10-minute mark so both sides brown evenly. Watch for a deep golden color — baking longer at too-low a temperature will dry them out, while too hot without turning risks burning one side.

While the taquitos bake, make the Rotel dipping sauce: In a small saucepan melt the butter over medium heat. Add the remaining 1/4 tsp salt and 1/4 tsp black pepper, then add the diced Rotel and any juices. Simmer gently, stirring occasionally, until reduced by about a quarter and slightly thickened, 8–10 minutes. Finish by stirring in 1/4 cup (about 30 g) of shredded cheese off the heat until melted and smooth — the cheese enriches and slightly thickens the sauce so it clings to the taquito when dipped.

Remove the taquitos from the oven and let rest 2 minutes (this allows residual steam to settle so they stay crisp). Serve 4 taquitos per person arranged on a platter with a bowl of warm Rotel dipping sauce. Finish with an extra sprinkle of cheese or a pinch of smoked paprika if desired.