Heat your grill pan or a saucepan to cook your panini. If using a pan, also provide a lid.
Mix the diced tomatoes with the gochujang. Finely chop the spring onions and dice the avocado.
Drain the mozzarella and also cut it into cubes.
Slice the zucchini into long strips. Season with salt and pepper, drizzle with olive oil, and grill them.
Spread the opened panini with the tomato sauce. Distribute the avocado cubes on top and mash them with a fork.
Sprinkle with the spring onions and mozzarella cubes. Place the top piece of the panini on and grill.