In a mason jar or small bowl, combine the minced shallot, garlic, thyme, parsley, apple cider vinegar, Greek yogurt, and buttermilk. Shake or whisk until the dressing becomes smooth and creamy. Taste and adjust with sea salt and freshly ground black pepper, then refrigerate it while preparing the salad to let the flavors develop.
Rinse the lettuce thoroughly and dry it completely before tearing it into bite-sized pieces. Thinly slice the radishes and asparagus, grate the carrots, and measure out the peas. Keeping everything evenly sliced ensures each bite has balanced flavor and texture.
Place the lettuce in a large bowl and add the radishes, carrots, peas, and asparagus. Drizzle the chilled buttermilk dressing over the top and gently toss until everything is lightly coated. Finish with a sprinkle of sprouts for garnish and serve immediately for maximum freshness.