Place 1/2 of the white beans into a food processor with the garlic, basil, olive oil and pinch of salt pepper. Pulse a few times until mostly combined. Add in the rest of the beans and pulse together 2-3 more times to incorporate the beans while keeping some texture.
Toast the sourdough bread.
Smear on white bean mixture and top with tomato slices and avocado. Sprinkle with salt/pepper.