Inspect baby spinach and remove any damaged stems or leaves. Rinse thoroughly in a large bowl of cold water, then gently spin dry in a salad spinner or pat dry with clean kitchen towels until leaves are mostly dry.

Slice vegetables

Halve the cherry tomatoes, thinly slice the cucumber and red onion. Dice the avocado and set aside; to slow browning, toss avocado gently with a squeeze of lemon juice (about 1/2 tsp) if desired.

To toast walnuts

Place walnuts in a dry skillet over medium heat. Toast, stirring frequently, until fragrant and lightly browned, about 3–4 minutes. Remove from heat and let cool slightly, then roughly chop.

Assemble salad

In a large serving bowl, combine the dried spinach, halved cherry tomatoes, sliced cucumber, sliced red onion, diced avocado, crumbled feta, and chopped toasted walnuts. Toss gently to distribute ingredients evenly.

Dressing

Make dressing by adding olive oil, fresh lemon juice, Dijon mustard, honey or maple syrup, minced garlic, salt, and black pepper to a small jar or bowl. Whisk vigorously (or shake in a lidded jar) until the dressing is emulsified and slightly thickened, about 20–30 seconds. Taste and adjust seasoning: add more salt, lemon, or honey as needed.

If the dressing is too sharp, whisk in an additional 1/2 teaspoon of olive oil or 1/4 teaspoon honey to mellow. If too thick, thin with up to 1 teaspoon of warm water.

Pour about half the dressing over the assembled salad and toss gently to coat leaves and distribute toppings. Add more dressing gradually to taste — you may not need the entire amount.

Finish

Transfer tossed salad to a serving platter or leave in the bowl. Sprinkle lemon zest and extra cracked pepper over the top if using. Serve immediately so the spinach remains crisp.

Leftover dressing can be refrigerated in a sealed container for up to 5 days. Store any leftover salad components separately if you plan to assemble later to avoid sogginess.