HEAT A DRIZZLE OF OIL IN A LARGE, OVEN-PROOF FRY-PAN ON MEDIUM-HIGH HEAT. COOK ONION FOR 3–4 MINUTES, UNTIL GOLDEN. ADD CHILLI (IF USING), CARROTS AND CAPSICUM AND COOK FOR A FURTHER 4–5 MINUTES, UNTIL VEGGIES ARE SOFT (ADD A SPLASH OF WATER IF VEGGIES START TO STICK).
STIR IN MEXICAN SPICE MIX, CHILLI BEANS AND TOMATOES AND SIMMER FOR ABOUT 5 MINUTES, UNTIL SAUCE HAS THICKENED LIGHTLY. SEASON TO TASTE WITH SALT AND PEPPER.
IN A SMALL BOWL MASH AVOCADO WITH 1–2 TEASPOONS LEMON JUICE. SEASON WITH SALT AND PEPPER.
PLACE A HANDFUL OF CORN CHIPS INTO EACH BOWL AND SPOON OVER THE BEAN AND VEGGIE MIXTURE. TOP WITH A SMALL HANDFUL OF SHREDDED LETTUCE, MASHED AVOCADO, AND CORIANDER.