Place the red onion and garlic in the seasoned rice vinegar and set aside for 15 minutes.
Cut the cherry tomatoes in half lengthwise and toss with 2 tablespoons olive oil, salt and pepper.
Preheat a non-stick pan over high heat. When very hot, toss in the tomatoes and allow them to sit for a few minutes. Toss as they begin to char and remove from the pan when they begin to collapse and have some charred edges. Set aside.
Combine the drained mixed beans with the onion, garlic, and all the juices in the bowl. Add 2 tablespoons of olive oil, and lemon juice. This bean salad can be made several days in advance and refrigerated. It actually tastes better if made at least 1 hour before using.
Gently fold in the mixed herb, charred tomatoes, and feta cheese. Season to taste with salt and Aleppo pepper.
Brush the slices of bread with olive oil and toast under a broiler or grill in a grill pan on both sides.
Crush ½ an avocado directly on each slice of toast.
Spoon ⅙ of the bean salad on top of the avocado, sprinkling with more feta if desired.
Serve immediately.
