Preheat the oven to 400°F (200°C). Line an 8x12-inch (20x30cm) baking dish with baking paper.
Beat the eggs with the taco seasoning. Drain the corn, slice 1 onion into rings and dice the other.
Mix the corn into the eggs and transfer them into the baking dish. Place the onion rings on top of the eggs and place the dish in the oven to bake for 25 minutes. Cover the dish with foil if the frittata is getting too dark.
Meanwhile, mix the minced meat with the diced onion and ground coriander. Divide the minced meat mixture into 8 portions and form it into oblong shapes. Heat the oil in a skillet or frying pan over medium-high heat and cook for 8 minutes, turning regularly, until the meat is done.
Place the chopped tomatoes and sliced spring onions into a small bowl. Add in the lime zest and 2 tablespoons of lime juice. Season to taste with salt and pepper and mix well. Serve the frittata with the beef bites and tomato salad.