1 small shallot or 1/4 red onion, thinly sliced
1.5 tbsp sherry or red wine vinegar
Freshly ground black pepper
10oz frozen broccoli florets
3 tbsp olive oil
1 garlic clove
2 tbsp mayo
1 tsp Sriracha (optional)
2 ciabatta small loaves
4 slices cheddar
Combine shallot, vinegar, sugar, and a pinch of salt and pepper in a small bowl. Stir to combine; set aside.
Heat oil in a large ovenproof skillet over medium-high. Add frozen broccoli and season with salt. Cook, stirring occasionally, until browned in spots, about 3 minutes. Reduce heat to medium, add ¼ cup water, and cover. Cook until tender, about 2 minutes. Reduce heat to low and uncover. Add in minced garlic and shallot mixture. Cook, stirring, until vinegar is mostly evaporated, about 15 seconds. Transfer to a bowl.
Optional step – Mix mayonnaise and chili sauce in a small bowl. Taste and add more chili sauce if desired.
Broil ciabatta, cut side up. Remove from oven and spread mayo mixture over. Spoon broccoli mixture on top, going all the way to the edges (don’t be afraid to pile it on). Drape a slice of cheese over (tear in half if needed).
Broil, watching carefully, until cheese is bubbling and browned, about 3 minutes. Season with pepper.