01 - Whisk together olive oil, balsamic vinegar, honey, salt, and pepper in a small bowl. Brush the mixture evenly over chicken breasts and plum halves.
02 - Preheat grill to medium-high heat. Lightly oil the grates to prevent sticking.
03 - Grill chicken for 6–7 minutes per side until internal temperature reaches 165°F. Simultaneously grill plum halves cut-side down for 2–3 minutes until charred and softened. Let rest briefly.
04 - Combine avocado, basil, lemon juice, garlic, olive oil, salt, and pepper in a blender. Blend until smooth, adding water as needed to achieve pourable consistency. Adjust seasoning to taste.
05 - Slice grilled chicken and plums. Arrange on plates and drizzle generously with basil avocado sauce. Garnish with additional basil leaves and serve with lemon wedges on the side.