Preheat oven to 375F.

Stir together cumin, coriander, salt, and pepper in a small bowl.

Set the spice mixture aside.

In a large bowl, toss zucchini, bell peppers, onions, and olive oil together.

Add the cumin mixture to the vegetables and toss to coat evenly.

Divide the vegetables between 2 baking sheets.

Roast for 30 to 45 minutes, or until tender and golden brown, turning the vegetables once or twice and rotating baking sheets from top to bottom.

Let the roasted vegetables cool.

Heat 1 tsp of olive oil in a small skillet over medium heat.

Add minced garlic and cook for 30 seconds to 2 minutes, or until translucent and fragrant.

Add cannellini beans and coarsely mash them.

Stir in 3/4 cup of water and cook for 10 minutes, or until the mixture is the consistency of refried beans, stirring occasionally.

Stir in lemon juice and let cool.

To assemble the sandwiches, spread 2 Tbs of bean spread on each bread slice.

Top 4 bread slices with 1 cup of roasted vegetables, 2 or 3 tomato slices, and 1/2 cup of arugula.

Place the remaining 4 bread slices on top.

Cut in half to serve.