Lentil Croquettes

Name: Lentil Croquettes
Ingredients: 3 tablespoons extra-virgin olive oil; 2 cups chopped onion; 1 cup chopped carrot; 1 cup chopped celery; 1 green bell pepper, chopped; 6 cloves garlic, chopped; 1 pound lentils, rinsed and drained; Salt; Vegetable oil, for frying; 1 egg, beaten; All-purpose flour; Breadcrumbs; Chili powder; Beet Tzatziki, for serving, recipe follows; Guacamole, for serving, recipe follows; 4 beets; Olive oil, for drizzling; 2 cups plain Greek yogurt; 1 cup seeded, diced cucumber; 2 tablespoons lemon juice; 1 teaspoon white wine vinegar; 2 cloves garlic, chopped; 4 avocados; 1 teaspoon olive oil; 1 lime, juiced; 1 jalapeño, seeded and finely chopped; Chopped fresh cilantro; Salt and pepper