Preheat oven to roast at 400 degrees F. Line a baking sheet with foil, coat with cooking spray, and set aside.
In a medium to large mixing bowl, toss the sliced tomatoes with olive oil.
Spread the tomatoes in one layer on the prepared baking sheet. Sprinkle with garlic, rosemary, salt, and pepper.
Roast on the top shelf of the oven for 15 to 20 minutes, rotating the pan midway through cooking to ensure even cooking. Remove from the oven and set aside until ready to assemble sandwiches.
While tomatoes are cooking, cook the halloumi and eggs.
To cook halloumi: Heat a cast-iron or nonstick skillet or grilling pan over medium-high heat. When the skillet is hot, add halloumi slices in one layer (you may need to work in batches depending on the size of your pan) and cook about 2 to 3 minutes until bottom is golden brown. Flip the cheese and cook until other side is golden brown, another 2 to 3 minutes. (Note: the cheese should not melt.) Set cheese aside.
To poach eggs: Fill a medium saucepan with a shallow layer of water and a splash of vinegar. Bring water to a boil and immediately reduce to a simmer. Crack egg into a small dish (I like to cook them one or two at a time). When the water comes to a simmer, gently tip the dish into the water so the egg can slide out. Gently simmer the egg for about 3 to 4 minutes until the egg white is firm but the yolk is still runny. Use a slotted spoon to remove poached egg(s) to a plate and repeat with the remaining eggs.
When finished cooking the halloumi cheese, place bread in the skillet and toast on both sides.
In a medium bowl, mash together avocado, lime juice, and a pinch of salt. Set aside.
To assemble egg & cheese: Spread mashed avocado on each slice of toasted bread. Top with 2 slices of cooked halloumi cheese, 2 to 3 roasted tomatoes, and 2 poached eggs. Season with a pinch of Kosher salt, freshly ground pepper, and microgreens if desired.
Halloumi is a brined cheese made from a mixture of cow's, goat's, and sheep's milk. It is very popular in Mediterranean cooking.
Rosemary Garlic Roasted Tomatoes can be made in advance and warmed up before using.
Note: If you have a compromised immune system, be careful of undercooked eggs. If you can find pasteurized eggs, those are best for eggs you will serve with a runny yolk.