Prepare the Produce: Thoroughly rinse and drain the canned black beans and corn using a colander. Halve the grape tomatoes. Roughly chop the romaine and spinach if the leaves are large. Set all prepared components aside.
Craft the Creamy Vinaigrette: In the canister of a high-speed blender, combine the flesh of 1 ½ avocados, Greek yogurt, cilantro, chopped scallions, garlic cloves, fresh lime juice, agave nectar, ground cumin, and sea salt.
Blend to Perfection: Secure the lid and blend on high for 45–60 seconds, pausing to scrape down the sides if necessary. Continue until the mixture is completely uniform, creamy, and a vibrant pale green. If the dressing is too thick, add a tablespoon of cool water and blend again to reach a pourable consistency.
Build the Salad Base: In a large salad bowl, add the chopped romaine and spinach blend. You can either toss the greens with about half of the prepared dressing now or serve it on the side for individual preference.
Arrange the Toppings: Artfully arrange the rinsed black beans, drained corn, and halved grape tomatoes in separate sections on top of the bed of greens. This presentation creates a visually appealing mosaic of color and texture.
Dress and Garnish: Drizzle the remaining dressing over the arranged toppings. Finish with a generous sprinkle of toasted pepitas, adding a delightful crunch to the final dish. Serve immediately.