In a small bowl, whisk together the olive oil, lime juice, minced garlic, honey, and salt until emulsified and the honey is fully dissolved. This dressing can be made up to a few hours ahead, but I find the garlic flavor is brightest when made just before serving, so I don't recommend making it too far in advance.
While the dressing rests, prepare all your fresh ingredients: cut the watermelon into 1-inch cubes, slice the cucumber into 1/2-inch half-moons, thinly slice the red onion, seed and mince the jalapeño, dice the avocado into 1/2-inch pieces, and tear the fresh mint leaves into bite-sized pieces. Keep the avocado separate until just before assembly to prevent browning.
Arrange the watermelon, cucumber, and red onion on a serving plate or in a large bowl. Pour about half of the lime-garlic dressing from Step 1 over these base ingredients and gently toss to coat evenly. This initial dressing helps season the vegetables and begin building flavor.
Top the dressed salad with the crumbled feta, diced avocado from Step 2, minced jalapeño, and torn mint leaves. Drizzle the remaining dressing over the top and season with the pinch of salt and freshly cracked black pepper. I like to add the pepper generously—it brings out the sweetness of the watermelon and adds a pleasant bite that balances the rich feta and creamy avocado.